Saratoga Spittlebug; Feedings Scars; Damage from Spittlebug Infestation; Spittlebug Nymph in ♦^ \^* Spittlemass

$Saratoga Spittlebug; Feedings Scars; Damage from Spittlebug Infestation; Spittlebug Nymph in ♦^ \^* Spittlemass$

íí\f^íÍAU

United States III Department of Agriculture Saratoga Forest Service Spittlebug— Agriculture Handbook No. 657 Its Ecology and Management Persons of any race, color, national origin, sex, age, religion, or with any handicapping condition are welcome to use and enjoy all facilities, programs, and services of the USDA. Discrimination in any form is strictly against agency policy, and should be reported to the Secretary of Agriculture, Washington, DC 20250.

Cover (clockwise from top \eit)^Saratoga spittlebug; feedings scars; damage from spittlebug infestation; spittlebug nymph in ♦^ \^* spittlemass. Saratoga Spíttiebug— Its Ecology and Management

Louis F. Wilson, principal insect ecologist U.S. Department of Agriculture, Forest Service North Central Forest Experiment Station East Lansing, MI

United States Department of Agriculture Forest Service

Agriculture Handbook No. 657

April 1987 Contents

Page Page

Introduction 1 Management 44 Biology, Distribution, Hosts, and Management Guidelines 44 Damage 2 Socloeconomic Considerations 44 Description of the Insect 2 Timber 44 Taxonomy 2 Wildlife 44 Egg 2 Water yield and quality 45 Nymphs 2 Recreation and visual quality 45 Adults 3 Selecting a Management Strategy 45 Distribution 4 Unplanted sites 45 Hosts 4 Plantations 46 Primary hosts 4 Christmas trees 47 Alternate hosts 4 Literature Cited 48 Interim alternate hosts 7 Field Survey Forms 52 Life History and Habits 9 Risk-Rating Survey 53 Egg stage 9 Nymphal Appraisal Survey 55 Nymphal stages 13 Adult stage 15 Host Damage 17 The feeding puncture wound 17 Physical injury 18 Physiological injury 22 Stand damage 23 Population Ecology, Dynamics, and Control 29 Ecological IVIodel 29 Population Dynamics IVIodel 30 Prevention and Control Tactics 35 Prevention 35 Cultural and biological control 35 Chemical control 35 Herbicidal control 37 Surveillance 38 Survey Methods 38 Risk 38 Risk-rating 38 Aerial risk-rating 39 Detection 40 Detection survey 40 Aerial detection survey 41 Evaluation 41 Feeding scar appraisal survey 41 Nymphal appraisal survey 41 Suppression 42 Predicting control date 42 Pre- and post-control appraisal survey ... 43 Introduction

The Saratoga spittlebug, Aphrophora saratogensis (Fitch), is the most destructive sap-sucking forest insect pest of pines in eastern North America. Taxonomically described as a distinct species in the 1850's, it remained unnoticed until 1941, when Secrest (1943, 1944) linked red and jack pine mortality to feeding by spittlebugs. Pines planted extensively in the 1930's, especially in the Lake States region, provided abundant even-aged host material on which the adults fed. In addition, these pines were planted in old fields where abundant ground cover was available as food for the nymphs. This combination permitted the spittlebug population to reach epidemic levels, and many trees were killed in the early 1940's in Michigan and Wisconsin.

The spittlebug has damaged planted pines in most of the North- eastern States and in adjacent Canadian provinces. Its recogni- tion as a pest, in 1941, occurred almost simultaneously with the uncovering of the pesticide value of DDT. Because DDT was highly effective against the spittlebug, it and other chemicals were sprayed almost annually in the 25-year period following (Fowler and others 1986). In spite of these control programs, the spittlebug still ruins many pine stands each year and continues to affect thousands of acres of pine planted for pulp, timber, and other forest products. Much of the problem remains because pine is frequently planted on high-risk sites and because integrated pest management tactics and economic appraisals have not been available until recently.

Research has provided much new information about the behavior, habits, and ecology of the Saratoga spittlebug. Today management guidelines are available that are compatible with contemporary forest management practices. Such information is assembled and presented in this publication. It is divided into four major parts: • The spittlebug's biology, distribution, and hosts, and symptoms of the damage it causes. • The behavior of the insect as a population (this part includes various preventive and control tactics, both historical and practical). • Survey procedures useful for assessing spittlebug populations. • Management guidelines and socioeconomic considerations useful for selecting appropriate management strategies. Biology, Distribution, Hosts, and Damage

Description of the Insect

Taxonomy—Aphrophora saratogensis (Fitch) is in the order Homoptera, family Cercopidae, subfamily Aphrophorinae. The approved common name in North America (Entomological Society of America) is Saratoga spittlebug. The French name, used primarily in Quebec, is cercope Saratoga. Fitch (1893) originally described the species as Lepyronia saratogensis from specimens taken in Saratoga County, New York. Doering (1941) synonymized Ptyelus gelidus Walker from a list of Homoptera of 1851. Moore (1956) synonymized A. detritus (Walker) whereas Doering (1941) considered detritus to be distinct, but closely related to saratogensis. She says the two species can be separated by color; detritus lacks the broad white markings and other characteristics of the typical saratogensis adult. In this publication, I consider detritus as distinct from saratogensis, the former being a southern species, and the latter a northern species.

The genus Aphrophora was described by Germar in 1821 (Doer- ing 1930). Though Fitch (1893) originally placed saratogensis in the genus Lepyronia, he later pointed out that it should belong in Aphrophora because it fits Germar's description more closely. Still later, other taxonomists attempted to straighten out confu- sions in the genus and synonymies of saratogensis with mixed degrees of success (Walley 1928; Ball 1928, 1934; Doering 1930, 1941). Figure 1—Saratoga spittlebug egg. Egg—The egg is an elongate tapering ellipsoid, shaped somewhat like a teardrop—rounded at the large end and tapering to a curved blunt point at the other end (fig. 1). It averages front cover. Anderson (1947b) lists the following head capsule about 1.8 mm long and 0.6 mm wide. Immediately after widths for the five instars: oviposition the egg is soft and depressed along the long axis; later it turns plump and turgid. At first it is a glistening light Instar Width (mm) Range (mm) buff to yellow from pigment in the endochorion, but after over- wintering the pigment changes to red or purple. Eggs become 1 2.0 1.7-2.1 deep red or deep purple if partially exposed to sun and weather. 2 3.0 2.8-3.5 3 4.3 3.7-5.0 Eggs dissected from gravid females contain well-developed em- 4 5.8 5.4-6.5 bryos that average 0.6 mm long, the size at which they enter 5 7.5 6.6-8.1 winter for their obligatory diapause (Giese and WUson 1957). Viable eggs more than a few days old contain a red spot that The striking crimson abdomen is a distinct characteristic of the can be seen through the transparent chorion at the pointed end. first four nymphal instars. The head, thoracic tergites, portions The spot is spherical and appears to be granular, noncellular, of the leg segments, and pleural lobes of the abdomen are dark and separated from the embryo by undifferentiated yolk. The gray to jet black. The median line on the head and thorax is spot apparently is the source of red pigment for the abdominal light brown, as are the zones around the eyes and remaining region of the first four nymphal instars. portions of the leg segments. Following ecdysis, the dark pigment is absent for a short period and those parts usually black Nymphs—The five nymphal instars range in body length from are then tan or whitish. The compound eyes are scarlet. about 2.0 mm (first instar) to almost 8.0 nun (fifth instar). Because lengths overlap between succeeding stages, markings The degree of dark markings on the pleural region of the caudal and head capsule measurements are more reliable distinguishing abdominal segments are useful for identifying the first four nym- characteristics. Typical nymphs are shown in figure 2 and on the phal instars (fig. 3). The abdomen of the^rji instar is entirely V IV

FIRST INSTAR SECOND INSTAR

THIRD INSTAR FOURTH INSTAR

Figure 3—Abdominal markings on first four nymphal instars. Ttie abdomens are crimson, the markings dark gray to black. Roman numerals indicate segments. Figure 2—Late-instar nymph of Saratoga spittlebug.

crimson with the gray-black pigment confined to the caudal tergite (segment IX). Pigment is found on all pleurites of the second instar, but most abundantly on segment VIII and also abundantly on segment VII. On the third instar pigment is most abundant on segments VI, VII, and VIII. On the fourth instar pigment is more abundant on segments IV to VIII, and the nymph shows early development of wing pads. The fifih instar (not shown in fig. 3) has a uniformly tan or dark brown abdomen. Figure A—!\/lorphological characteristics of the Saratoga spittlebug. A—Head showing arrow-shaped marking. B—Female sternltes Initially, the fifth-instar nymph has a pale red abdomen and a and ovipositor. C—Maie sternltes. tan thorax, head, and legs. Later the entire insect becomes uniformly brown. As it ages further, it tends to darken to a deep mahogany. The crimson color actually remains but is masked by graded between the two. Most, however, have some striping. the melanistic pigment in the cuticle (Anderson 1947b). Females are generally larger than males and readily distin- guished by their sword-shaped ovipositor (fig. 4B), which is Adults—Fitch (1893) originally characterized the adult Saratoga about one-fourth the length of the abdomen. Females average spittlebug. The adult is smoothly tapered and somewhat boat- 9.7 mm long (range 9.0-10.31) and males average 8.9 mm shaped from a top view. Adults of both sexes are primarily (range 8.0-9.5). Females not well marked with the median brown but are marked variously with distinct tan, silvery-white, stripe can be separated from other species by the length of the and creamy blotches, stripes, and bands. A distinct, irregularly vertex and the ratio of head length to pronotum length (Doering mottled transverse silvery band highlights each hemelytron 1941). Males are readily separable from other Aphrophora by (anterior wing cover). The major distinguishing mark is a broad the shape of the genital plates (fig. 4C) as well as by markings. dorsal median cream-colored stripe on the vertex of the head that extends onto the pronotum of the thorax. The stripe is Several spittlebugs occur on northern pines, but only the arrow-like in most well-marked specimens (fig. 4A and front Saratoga spittlebug and the pine spittlebug Aphrophora cribrata cover). Walker are abundant and economically important. The pine spittlebug, because it prefers Scotch pine and jack pine, is rare on Fitch (1893) discriminated both light and dark specimens, the red pine and does not require an alternate host. A. gélida latter form having an iilmost obsolete stripe. He saw others that (Walker) is another, rarer species that looks like, behaves like. and is sympatric with the Saratoga spittlebug (Putman 1953). pines. In one test, however, spittlebugs killed white pine shoots However, it lacks the cream-colored stripe on the head and after a week of feeding in sleeve cages placed over white pine thorax. branches. Anderson (1945a) also suggested that eastern white pine is far inferior to red pine as a host. Using nymphal abun- Distribution dance on the alternate hosts beneath ñve adjacent pairs of red and white pines as an indicator of preference, he measured six The Saratoga spittlebug is native to eastern North America. The times as many nymphs beneath the red pines (table 1). On distribution generally corresponds to the range of its major sweetfem alone, nymphs per stem were seven times more abun- native hosts. In the United States, it is present from Maine south dant beneath red pine than under white pine. to New Jersey, westward through Pennsylvania and the northern portions of Ohio, Indiana, and Illinois, and northwestward to Table '\—Saratoga spittlebug nymptial density beneath five adja- Minnesota. It is probably not present in Maryland, Washington, cent pairs of red and eastern white pine trees'^ DC, and southward (Doering 1941). In Canada, it is found in No. of the southern parts of all the provinces from the east coast to nymphs per plant Manitoba. Historically, the spittlebug has been a pest problem in Nymphal host Red pine White pine the Lake States and Ontario and to a lesser degree in Penn- sylvania, New York, and Maine. Sweetfern 3.5 0.5 Aster .6 0 .2 Hosts Blueberry .5 Bracken fern .4 .1 Barren strawberry .3 0 The Saratoga spittlebug requires two different hosts for complete Wild lettuce .2 .1 development and survival—one for the nymphal stages and one for the adult. The adult needs a conifer on which to feed, mate, iTaken from Roger F. Anderson, Biology of the Saratoga spittle insect, 1945. and oviposit. The conifer, usually a pine, is called the primary (or adult) host. The nymph feeds on the sap of various woody Both Scotch pine, P. sylvestris L., and Austrian pine, P. nigra and herbaceous plants of the forest floor beneath or adjacent to var. austríaca A. & C, are occasional primary hosts in the conifer host. These hosts are called the alternate (or nym- Christmas tree or other plantations when alternate hosts are pres- phal) hosts. ent. In a Scotch pine planting that showed heavy shoot flagging, the stand was infested by both the Saratoga spittlebug and the Primary Aiosis—The Saratoga spittlebug's primary hosts are pine spittlebug, and the needles showed signs of Diplodia sp. in- pines but it sometimes feeds intermittently on other conifers, festation, which is frequentiy associated with pine spitflebug particularly when these other conifers are growing along with feeding. the primary host pines. Since the extensive planting of pines in the 1930's, red pine, Pinus resinosa Ait., has been the most im- Pitch pine, P. rígida Mill., was recorded as a host by Fitch portant primary host from the standpoints of feeding preference (1893), and tamarack, Larix laricina (Du Roi) K. Koch, by and economic injury. Jack pine, P. banksiana Lamb., is the Doering (1942). I have seen a few feeding punctures but no second-most important host. The spittlebug readily feeds on jack injury on tamarack. pine, and it stunts and kills some trees in both pure and mixed stands. More trees are usually killed in mixed stands of red and Adult spittlebugs have been taken from balsam fir, Abies jack pines, however. Anderson (1947a) counted 5.5 and 1.9 balsamea (L.) Mill., and northern white-cedar. Thuja occiden- feeding punctures per square centimeter, for the red and jack talis L., when growing in the vicinity of infested red pines pines, respectively, suggesting a nearly threefold preference for (Ewan 1961). No feeding on these conifers has been reported. red pine. Ewan (1961) also ranked red pines far above jack pines for spittlebug preference. He noted that in mixed plant- Alternate hosts—Hundreds of plant species likely qualify as ings, even when red pines were severely injured or killed, jack alternate hosts of the spittlebug nymph. Ewan (1961) suggested pines rarely showed more than some dead shoots and appeared that if a list were compiled, it would include nearly every herb, in little danger of dying or having their tops die. Also, jack pine shrub, tree seedling, and fern growing in pine stands. This state- usually dies from the spittlebug-associated burn blight fungus ment is almost valid, but some plants are so rare that they and not directly from the spittlebug. would not commonly become hosts of the nymphs.

Eastern white pine, P. strobus L., is another native pine that Anderson (1947b) encountered and listed about 35 plant species will support adult spittlebugs, but the insects seldom attack white that served as hosts during all or part of the nymphal period. pines when they are isolated from red or jack pines. Heavily in- Examining 91 one-tenth-acre plots in 60 red pine plantations injured white pines have been found near heavily infested red fested with the spittlebug, Kennedy and Wilson (1971) recorded pines in Pennsylvania (Ewan 1961). I have noticed feeding punc- an abundance of about 30 species of plants covering the forest tures on white pines but have not seen flagged or dead white floor (table 2). Grasses and sedges were present in all plots and Table 2—Abundance of understory vegetation in 91 Saratoga spittlebug plots in ttie Lower Peninsula of Michigan

Plots with Understory these species Percentage of vegetation Scientific name (%) ground cover Grasses, sedges Graminea; Carex spp. 100 26 Sweetfern Comptonia peregrina (L.) Coult. 69 21 Brambles Rubus spp. 46 11 Mosses, lichens Musci, Lycopodium spp., Cladonia spp. 43 11 Misc. forbs Soiidago spp., Aster spp., Potentilla spp., Rumex sp.. Centaurea sp., Anemone sp., Gaultheria sp., Achillea sp., Convolvulus sp., ef a/. 100 10 Bracken fern Pteridium aquilinum (L.) Kuhn 23 6 Blueberry Vaccinium spp. 17 4 Strawberry Fragaria Virginian a Dus. 30 3 Sand cherry Prunus pumila L. 18 3 Sumac fî/71/s spp. 14 2 Orange hawkweed Hieracium aurantiacum L. 7 2 Small trees, shrubs Prunus spp., Sa//x spp., Populus spp.

Total 100 covered an average of 26 percent of the ground. Sweetfern and Other plants able to support nymphs through their ñill brambles together occupied about 32 percent of the ground developmental period are less abundant than sweetfern, cover; 69 percent and 46 percent, respectively, of the 91 plots brambles, and blueberry, and also appear to have less survival contained these species. The remaining 42 percent of the ground value for the nymphs. Sheep sorrel and old-field cinquefoil are cover consisted of other miscellaneous plants such as forbs, particularly poor hosts and are usually abandoned long before ferns, shrubs, small trees, mosses, and lichens (table 2). Secrest the nymphs mature. (1944) specified that sw^eetfern was the principal nymphal host, and Ewan (1961) believed that both sweetfern and brambles The following discussion gives more information on the specific were necessary for spittlebug population buildup. They believed plants that support ftill nymphal development and includes obser- that other host plants were less important but could contribute to vations on the survival rates of nymphs on different species. population increase where they were abundant. Unless specified, the information is from Kennedy and Wilson (1971) and Wilson and others (1977). Wilson and others (1977), after extensive host preference tests, concluded that the ground cover plants in pine stands vary in Sweetfern—Most investigators have concluded that sweetfern is their support of nymphal development and survival. They the principal alternate host plant of the spittlebug (fig. 5 and categorized the understory vegetation as plants that support the back cover). Anderson (1947b) easily reared adults on this nymphs through full development, plants that support the species from third and fourth nymphal instars, and he and other nymphs through part of their development, and plants that do investigators noted that this species had large spittlemasses and not support nymphs during any part of their development abundant nymphs in the fifth stadium. Wilson and others (1977) (table 3). reported that sweetfern pollen was nearly completely shed and buds were beginning to swell when nymphs eclosed and began Several plant species provide suitable conditions for complete to seek hosts. First-instar nymphs avoid the old stems and nymphal development and are the true alternate hosts of the spit- search out first- or second-year stems for feeding. Nymphal sur- tlebug. Sweetfern, brambles, and blueberry are the most vival is always excellent if clusters have at least some young numerous of the true alternate hosts in the Lake States region. stems. The nymphs feed on both old and new shoots after the Nymphs survive best on sweetfern. All other true alternate third instar. hosts, except willow, do not support nymphs as well as sweetfern. Survival on willow is exceptionally high, surpassing Willow—Anderson (1947b) notes that willow (Salix humilis) was sweetfern in most cases. This suggests that willow also might be an excellent alternate host and found more last-instar nymphs on capable of supporting high population buildup. However, young it than on sweetfern. He also easily reared fourth instars to willow is rare in pine stands, occupying only about 2 or 3 per- adulthood on this plant. Leaves of Salix are just opening when cent of the forest vegetation, and sufficient numbers of willow the nymphs eclose. Late instars feed on old stems but all stages are seldom available to permit high population buildup. prefer the young suckers. The survival rate is very high, ex- Table 3—Plants supporting and not supporting Saratoga spittlebug Fly honeysuckle Lonicera canadensis Marsh. nymphal development Scarlet painted cup Castilieja coccínea (L.) Spreng. Common anemone Anemone canadensis L. Common name Scientific name White clover Trifolium repens L. Lambkill Kalmia angustifolia L. Viburnum cassinoides L. Plants supporting full nymphal development (true alternate hosts) Wlld-ralsin Gray birch Betuia populifolla Marsh. Black chokecherry Pyrus melanocarpa (Michx.) Willd. Sweetfern Comptonia peregrina (L.) Goult. Canadian everlasting Antennaria canadensis Greene Willow Saiix spp. Bramble Rubus spp. Plants not supporting nymphal development (non-alternate hosts) Orange hawkweed Hieracium aurantiacum L. Low blueberry Vaccinium vacillans Torr. Grasses Gramineae Sourtop blueberry Vaccinium myrtilloides Michx. Sedges Carex spp. Golden rod Solldago spp. Cladonia spp. Sheep sorrel Rumex acetosella L. Lichens Musci Old-field cinquefoll Potentilla simplex MIchx. Mosses Lycopodium spp. Spotted knapweed Centaurea maculosa Lam. Clubmoss Leathery grapefern Botrychium multifidum (J. F. Gmel.) Everlasting Antennaria neglecta Greene Violet Viola adunca Sm. Meadowsweet Spiraea alba Du Roi Wild lettuce Lactuca canadensis L. 'Taken from Roger F. Anderson, The Saratoga Spittlebug, 1947 and J.P. Linnane and Prairie ragwort Senecio piattensis Nutt. E.A. Osgood, Controlling the Saratoga Spittlebug in Maine, 1976. Plants supporting partial nymphal development (Interim alternate hosts)

WIntergreen Gauitheria procumbens L. Swamp thistle CIrsium muticum MIchx. Upright cinquefoll Potentilla recta L. Bracken fern Pteridium aqulllnum (L.) Kuhn Common mullein Verbascum thapsus L. Figwort Scrophularia lanceolata Pursh Common yarrow Achillea miilefolium L. Westen yarrow Achillea lanuiosa Nutt. Shinleaf Pyrola asarifolia MIchx. Trailing arbutus Epigaea repens L. Silvery cinquefoll Potentilla argéntea L. Aster Aster spp. Wild columbine Aquilegia canadensis L. Dandelion Taraxacum officinale G.H. Weber Pearly everlasting Anaphalis margaritacea (L.) C. B. Clarke Wood anemone Anemone quinquefoiia L. Strawberry Fragaria virginiana Duchesne Grasses (few species) Gramineae

Plants supporting at least partial nymphal development^ '■^-^jfà^ " : ,*^^^p<î

Upland willow Salix humills Marsh. Fire weed Epiiobium angustifollum L. Figure 5—Sweetfern plant, the major alternate tiost of the Quaking aspen Populus tremuloldes MIchx. Saratoga spittlebug. Bastardtoadflax Comandra umbellate (L.) Nutt. Daisy fleabane Erigeron strlgosus Muhl. Smooth goldenrod Solldago júncea Ait. Dwarf goldenrod Solldago nemoralis Alt. Low bindweed Convolvulus splthamaeus L. ceeding that on sweetfern, suggesting that willow is the best of Large-leaved aster Aster macrophyllus L. all nymphal hosts. Barren strawberry Waldsteinia fragarioldes (MIchx.) Tratt. Brambles—Anderson (1947b) reared fourth-instar nymphs on Bush honeysuckle Diervilla lonicera Mill. Pussytoes Antennaria canadensis Greene brambles, and he detected fifth-instar nymphs in numbers second Common lousewort Pedicularls canadensis L. only to those on sweetfern and willow. Although the nymphs BIgtooth aspen Populus grandidentata Michx. establish on brambles shortly after eclosión, the leaves are less Whorled loosestrife Lyslmachia quadrifolla L. than 0.6 cm long, and new-growth canes are from about 2.5 to Common evening- 5.0 cm above the ground. Young nymphs feed on old canes first primrose Oenottiera biennis L. Beaked hazel Corylus cornuta Marsh. and move to new ones in the second and older instars. The sur- Smooth rose Rosa blanda Ait. vival rate is moderate to high on brambles. Orange hawkweed—Anderson (1947b) readily reared nymphs (1977) noticed that nymphal counts increased fourfold on some to adulthood, beginning with the fourth instars, on orange plants during the last instar, indicating a possible attraction for hawkweed. Ewan (1961) considered this plant one of the prin- the older nymphs. cipal spittlebug alternate hosts, but Kennedy and Wilson (1971) showed that it was not related to high population buildup. At Wild lettuce and barren strawberry—Anderson (1947b) easily nymphal eclosión, new hawkweed leaves are from 2.5 to 7.6 cm reared first-instar nymphs to adulthood on these hosts. Wilson long. Previous year's leaves are present but are often flaccid or and others (1977) reared only one insect to adulthood on wild partly injured from freezing. Nymphs in all instars readily lettuce. establish on this host, and the survival rate is generally high. Interim alternate hosts—Numerous understory plants support Blueberry—Anderson (1947b) placed fourth-instar nymphs on the nymphs through only parts of their development because of blueberry but was unable to rear them to adulthood. However, asynchronous life cycles of the insect and the host, nutrient or he noted firth-instar nymphs feeding on blueberry plants. chemical changes, and/or various physical properties of the Nymphs normally establish on the older woody stems, year-old plants. These we have designated as interim alternate hosts and stems, and new shoots. At eclosión, the new stems are from 0.6 many of these species may collectively occupy a large propor- to 2.5 cm tall and leaves are about 0.6 cm long. The new stems tion of the ground cover in pine stands. Bracken fern is one of are preferred and most nymphs move to them by the end of the most common of these species. Interim alternate hosts appear June. Survival to adulthood is moderate on blueberry. to be valuable to the nymphs because they provide some food and/or shelter from the elements and their enemies. Also, their Golden rod—Anderson (1947b) reared spittlebug nymphs from presence most likely increases the nymphs' chances for survival, the first instar to adulthood on goldenrod. Most goldenrod plants especially when true alternate hosts are sparse. are from 2.5 to 7.6 cm tall at the onset of nymphal eclosión. Survival is generally good to excellent on the succulent species, Nymphs may utilize interim host species during the early or late but older nymphs usually vacate the "woodier" goldenrod and portion of their development. For instance, the bracken fern, search for more suitable hosts. especially in shaded areas, is not always available to the nymphs at eclosión but is suitable as a host. In contrast, upright cinque- Sheep sorrel—Sheep sorrel often grows in large clusters near foil is available and highly suitable for early instar development red pine, and nymphs readily establish on it after eclosión. The but unsuitable for late-instar nymphs. The complete absence of plant appears healthy and succulent at eclosión time. By the time true alternate hosts, which is unlikely, may interfere with the of the insects' third stadium, however, the nymphs usually nymphs' survival and development to some extent, but nymphs vacate the plant in favor of more suitable hosts. Sheep sorrel can still survive by feeding on two or more species of interim supports a small percentage of the insects to adulthood, but it hosts. For example, nymphs encountering upright cinquefoil acts more like an interim alternate hosts (see below) because it shortly after eclosión could develop through the first or second mainly supports the young nymphs. instars on this plant, then vacate it and complete their development on a plant such as bracken fern. Old-field cinquefoil—Olá-ñdá cinquefoil is about 5.0 cm tall at nymphal eclosión, and the nymphs readily establish on it. Specific plants that support partial nymphal development, the in- Nymphs generally vacate cinquefoil in the later instars but can terim alternate hosts, are described and also listed in table 3. In complete their development on it if there are no other suitable addition, Anderson (1947b) and Linnane and Osgood (1976b) plants nearby. The survival rate to adulthood is moderate. listed and discussed numerous other hosts that support at least partial development (table 3). Spotted knapweed—Clusters of spotted knapweed are about 12.5 cm tall at nymphal eclosión. Nymphs easily establish on Wintergreen—Anderson (1947b) noted a few young nymphs on this host and develop to adulthood with moderate survival. Some wintergreen but later could not locate any fifth instars. This nymphs in the older instars vacate knapweed for more suitable plant is woody in the spring and barely suitable for early nym- hosts. phal feeding. In the absence of other hosts, some nymphs feed briefly on new shoots of wintergreen as they emerge. Survival is Everlasting—Anderson (1947b) was unable to rear first-instar usually poor if the nymph stays too long on this species. nymphs to adulthood on everlasting, but he noted a few plants had fifth-instar nymphs on them. Swamp thistle—Nymphs have difficulty establishing on swamp thistle after eclosión because the leaves are in a tight rosette Meadowsweet—Meadowsweet has leaves about 1.2 cm long at around the stem. Wilson and others (1977) examined 35 plants the onset of nymphal establishment. Old and new stems appear and concluded that the hairy or spiny leaves inhibit nymphal equally attractive to nymphs. Most nymphs remain on the host establishment for a week or more after eclosión. These spines to adulthood, and survival is moderate. Wilson and others spread out as the plant elongates, so second-instar nymphs are able to establish and grow to adulthood on swamp thistle. Most Strawberry—Nymphs readily establish on strawberry after eclo- late-instar nymphs, however, vacate the plant for more suitable sión when the new leaves are opening and the plants are from hosts. 5.0 to 7.5 cm tall. Survival, however, is poor. Anderson (1947b) found a few fifth instars on strawberry plants but was Upright cinquefoil—Nymphs readily establish on upright unsuccessfiil in rearing fourth instars to adulthood. Plakidas and cinquefoil but most vacate it or die. In mid-June this plant Smith (1928) record a spittlebug species as a pest of strawberry becomes tough and woody, which may contribute to its failure in Louisiana but the pest was probably Aphrophora detritus to maintain nymphs beyond that time. Walker (Doering 1941).

Bracken fern—Crosiers of bracken fern usually have not Prairie ragwort—Anderson (1947b) was unable to rear nymphs emerged above ground at the time of first-instar nymphal eclo- from the first instar to adulthood on prairie ragwort. He found a sión, and are thus not always available to the small nymphs. few plants with last instars on them. Wilson and others (1977) found that second- and third-instar nymphs would establish on this plant although they frequently Other plants—Anderson (1947b) lists several additional plants vacated it for more preferred hosts. Spittlebug nymphs, on which he found spittlemasses with nymphs in some stage of however, sometimes remain on bracken fern from late May, development (table 3). He observed early-instar nymphs on com- when they are in the second instar, until adult emergence in July mon lousewort and late-instar nymphs on fire weed, quaking if these plants are in the vicinity of hawkweed or other favored aspen, bastardtoadflax, daisy-fleabane, low bindweed, and bush alternate hosts. Anderson (1947b) reared a few nymphs from the honeysuckle. Further, he noted a few nymphs spittled on fourth instar to adulthood and noted that only a small percentage whorled loosestrife, common evening-primrose, beaked hazel, of fifth instars inhabited the ferns. smooth rose, fly honeysuckle, scarlet painted cup, white clover, and bigtooth aspen. Wilson and others (1977) found a few Common mullein and /ygworf—Both these hosts support young nymphs on low bindweed. Linnane and Osgood (1976b) nymphs for a short period after eclosión but become unsuitable list several alternate hosts common to the pine barrens of eastern thereafter. The hairy nature of mullein probably repels the Maine. Besides those found in the Lake States, they add lamb- nymphs. Anderson (1947b) found a few nymphs spittled on kill, wild raisin, gray birch, and black chokecherry to the nym- common mullein but remarked that it was not a favored host. phal hosts list.

Yarrow and s/7//7/eaf—These hosts easily support nymphs dur- Part of the ground cover in pine plantations consists of sedges, ing the first half of their development. Mortality increases after grasses, lichens, mosses, and miscellaneous forbs upon which that and those surviving readily vacate it for more suitable hosts. spittlebug nymphs do not feed; these plants are totally unsuitable Both species appear highly unsuitable by late June, but Anderson as alternate hosts (table 3). For instance, after a diligent search (1947b) noted a few plants of one species of yarrow (Achillea Wilson and others (1977) found no nymphs on violet. And when lanulosa) with fifth instars. placed on violet, the nymphs always abandoned it without feeding. Grasses also have always been considered unsuitable as Trailing arbutus and silvery cinquefoil—Nymphs establish and alternate hosts. Wilson and others (1977), however, found first develop on these plants but usually die by the third instar if they instars feeding on a few grasses in areas where forbs were don't move to other plants. scarce, and an occasional older nymph was observed feeding on grass even when other plants were available. These were Aster and wild columbine—These plants support the nymphs isolated feedings; grasses certainly would not support nymphs through three-quarters of their development. Nymphs then vacate for long. and do not reestablish on them, indicating that the conditions become totally unsuitable thereafter. Anderson (1947b) noted The major full-development alternate host plants have been ex- that first instar nymphs were abundant on Aster lindleyanus and amined as to their importance by comparing red pine injury (as A. macrophyllus but fifth-instar nymphs were very rare. Also, an index) to percentages of available alternate hosts (Kennedy he was unable to rear first-instar nymphs to adulthood on either and Wilson 1971). Not surprisingly, injury increased directly as species of aster. the percentage of sweetfern increased (up to 45 percent, after which spittlebug injury leveled off) (fig. 6A). Therefore, sweet- Dandelion, pearly everlasting, and wood anemone—These fern is important for spittlebug development or population three plant species support nymphs from eclosión to the late in- buildup. Other fiill-development nymphal hosts (bramble, orange stars, but all nymphs seem to vacate these plants by the last in- hawkweed, blueberry, etc.) collectively were also compared to star. Anderson (1947b) recorded only young nymphs on pearly pine injury. Interestingly, injury was not related to the availabil- everlasting and Anemone quinquefolia and older ones on ity of these hosts. That is, injury was always light no matter dandelion and Anemone canadensis. His attempts at rearing first how abundant the plants (fig. 6B). Because Ewan (1961) ranked instars to adults on Anemone failed. brambles and strawberry as primary alternate hosts, these were roo- N=38 A B X LU Q HEAVY HEAVY >-

MODERATE / MODERATE

LIGHT # LIGHT ___^ .^^_ n- 0-15 16-30 31-45 46-60 61-75 76-90 91-100 0-15 16-30 31-45 46-60 61-75 76-90 91-100 PERCENT SWEETFERN PERCENT MAJOR HOSTS (NO SWEETFERN)

c D X LU Û HEAVY HEAVY

MODERATE MODERATE

LIGHT ^,.>^''^*^^'^'^'*^^^^>^ LIGHT ^^^^^^..^^

0-15 16-30 31-45 46-60 61-75 76-90 91-100 0-15 16-30 31-45 46-60 61-75 76-90 91-100 PERCENT BRAMBLES (NO SWEETFERN) PERCENT STRAWBERRY (NO SWEETFERN)

Figure 6—Relationship of adult Saratoga spittlebug injury to density of sweetfern (A) other alternate hosts (B-D). Numbers in the upper right corners indicate the number of plots measured.

individually compared to injury but also showed no relationship STAGE WIN. APR. MAY JUNE JULY AUG. SEPT. WIN. to injury and abundance (fig. 6C, D). Kennedy and Wilson (1971) thus concluded that sweetfern was the most important of EGG the common full-development alternate hosts of the spittlebug. N,

Life History and Habits N2

The Saratoga spittlebug is univoltine—that is, it has only a N3 single generation each year. The developmental period, N4 however, varies somewhat. A 2- or 3-week variation of the life cycle, particularly in early spring, is not unusual over the in- N5 sect's north-south range or where there are diverse seasonal ADULT weather patterns (fig. 7). For instance, nymphal development may take from 40 to 70 days in different years or at different EGG latitudes. A few adults may emerge by the latter part of June and an occasional nymph may still be found in late August, indicating that stages tend to overlap broadly (Ewan 1961). Figure 7—-Generalized life cycle of the Saratoga spittlebug averaged for several years for central Michigan. Egg stage—Eggs are laid from about mid-July to late September, which is most of the adult spittlebug's life. After most of the adults have eclosed. Eggs are present in the field adult eclosión, eggs mature for about a week before they are from the onset of oviposition through fall and winter until late laid. The number of eggs laid usually peaks 2 or 3 weeks after May, as much as 10 months. The number of eggs laid by a female spittiebug is not known precisely because she may live for more than 2 months and lay eggs throughout that period. Anderson (1945a, 1947b) dissected spittlebugs weekly and counted the following number of fully developed oocytes:

Mean number of Date (1944) eggs/female July 9-15 5 July 16-22 0 July 23-29 1.3 July 30-August 5 5.0 August 6-12 12.8 August 13-19 5.2 August 20-26 12.8 August 27-September 2 10.7

He could not find fully developed eggs in young females until late July. Insects collected in August yielded an average of 9.7 eggs per female; some had up to 27 eggs and others were fully Figure 8—Saratoga spittiebug eggs protruding from scaies of a red pine bud. spent. Ewan (1961) dissected spittlebugs weekly and found an average of 14.6 eggs per female. He noted that the oocytes appeared to mature all at once, and suggested that the average he 237 found was probably the full egg complement, or close to it. The exact fecundity of the spittiebug has not yet been determined, but it seems to be less than 30 eggs.

On red pine, eggs are deposited mostly under the bud scales. Red pine is ideal for oviposition because it has numerous large buds with loose scales that are somewhat free of a heavy pitch coating. On jack pine the buds are too resinous for oviposition sites; instead the eggs are laid in the needle sheaths. Secrest (1944) erroneously reported that eggs were laid in shallow slits or under the bark scales of sweetfem. Others have not observed this. Also, spurious reports have been made of eggs being found under the bud scales and bark scales of various hardwoods (Anderson 1947b, Eaton 1955). If true, this must be a rare occurrence, perhaps a result of population pressure. Red pine buds harboring eggs appear bumpy on the surface, and, when heavily laden, some eggs protrude from the ends of the scales (fig. 8). When scales are peeled back, two to ten eggs can be seen with their points upward and lying side by side in rows or clusters (Ewan 1961).

Eggs are laid on every whorl of young red pine, but many more eggs are laid toward the top of the tree than toward the bottom. Distribution is apparently related to large buds and loose scales, which occur on the upper whorls (fig. 9). Small, tightly closed buds are free of eggs no matter where they are located on the tree.

About 33 to 50 percent of the eggs are under the scales of the buds on the terminal shoots. These percentages are particularly applicable for red pine. The single, very large terminal bud may harbor 25 percent of the eggs on a tree. At high population levels numerous eggs can be collected from a large terminal Figure 9—Scfiematic of young red pine trees showing location and numbers of Saratoga spittiebug eggs, summed from seven bud, occasionally up to 50 or more. The first-whorl buds harbor moderately infested trees. T = terminal. Numbers 1-7 refer to another 10 to 20 percent of the egg population. wfiorls.

10 Egg distribution varies up and down the tree depending upon the tlebug population tends to be higher in areas where sweetfern is insect population and tree size. Very lightly to moderately in- abundant. If the adults remain fairly close to where they grew fested trees (about 10 to 90 eggs per tree) have 60 to 65 percent up and if the females lay most of their eggs on the same tree, of the eggs on the terminal and first whorl (table 4). As the some trees would receive many eggs and others few or no population increases, proportionately fewer eggs are laid on the eggs—a situation encountered in overdispersed populations. Very upper whorls and more are laid on the lower, regardless of tree mobile adults and single or small-batch egg deposition would en- size (fig. 10). Also, large trees (or ones with several whorls of courage less aggregation. Spittlebugs, however, are poor ñyers, branches) have a broader distribution of the eggs than smaller but they can dart from tree to tree when disturbed. This suggests ones. For example, three-whorl trees have more than half of the that they do not move great distances. The position and proxim- eggs on the terminal shoot. Trees with more whorls have about ity of the eggs under the bud scales indicates that the females a third of the eggs on the terminal, with the rest distributed lay several eggs before moving to a new site. throughout the remaining branches (fig. 11). Eggs containing well-developed embryos overwinter in an Spittlebug eggs are aggregated or overdispersed on planted red obligatory diapause that normally ends after exposure to low pine trees (fig. 12) as indicated by Taylor's power law (1.00 is temperature. Eggs collected in fall and held at room temperature random) (Taylor 1961). This index for the spittlebug is 1.63 and or incubated at 80 °F do not differentiate beyond the embryonic indicates a strong aggregation, which may in part be due to stage in which they enter diapause (Ewan 1961). Giese and distribution of alternate hosts and perhaps also to oviposition Wilson (1957) held eggs at 80 °F and after 2 years found them habits. Sweetfern, particularly, is highly clumped and the spit- still viable but undifferentiated. Eggs collected in January or

WHORL

Figure "ïO^Distribution of Saratoga spittlebug eggs on young red pine trees witti three to eight whorls for five population density classes ranging from 10 eggs per tree (VL = very light) to 90 eggs per tree (VH = very heavy). (C = current growth leader). 30 7-74 2

31—753 r27 ► / 22

».28

rio

3 WHORLS 4 WHORLS 5 WHORLS 6 WHORLS 7 WHORLS

Figure ^^\--Distribution of Saratoga spittlebugs on red pine trees with various numbers of whorls per tree (various population levels are combined). later always developed, and nymphs hatched in 1 to 3 weeks The role of the red pine needle solution or other chemicals is after warming. Eggs collected in October did not hatch when ex- uncertain because eggs collected in fall do not hatch, even when posed to 0 °F for 1 week, but they did hatch when held at left inside red pine buds where resinous chemicals certainly 20 °F for 60 days (Ewan 1961). This indicates that a prolonged occur. exposure to moderately subfreezing temperature is more effective in stimulating diapause release than a brief exposure to very The red spot, which develops in the egg shortly after deposition, low temperature. Cold shock normally initiates the termination remains unchanged until diapause terminates. It is largest (0.2 to of diapause, but chemicals may play a minor role under certain 0.3 mm in diameter) from fall until spring and occupies about circumstances. Giese and Wilson (1957) reported a 50 percent 10 percent of the volume of the egg. When weather warms, the greater growth of embryos in eggs subjected to a solution of red spot decreases and after a short period disappears. In the macerated red pine needles. However, the eggs did not hatch. laboratory, Giese and Wilson (1957) noticed that the red spot

Table 4—Percenfagfe distribution of Saratoga spittlebug eggs on trees with six or seven whorls at five egg densities

Terminal and Very light Light Moderate Heavy Very heavy whorl (<11 eggs/tree) (11 -30 eggs/tree) (31 -90 eggs/tree) (91--120 eggs/tree) (>120 eggs/tree)

Terminal buds 54 46 40 23 28 First whorl buds 11 14 25 20 14 Second whorl buds 23 11 17 23 25 Third whorl buds 2 24 5 14 11 Fourth whorl buds 4 1 3 8 5 Fifth whorl buds 6 0 6 7 8 Sixth and seventh whorl buds 0 5 4 5 8

Columns may not add to exactly 100 percent because of rounding.

12 100 MEAN

Figure 12—Aggregation distribution of Saratoga spittiebug eggs based on ttie relation between intertree variance (s^) and mean (m) number of spittiebug eggs per tree. Dispersion index s^ = am''^'^ is based on Taylor's power law. Equation s2 = m indicates a random relation. diminished in proportion to the increase in length of the post- Nymphal stages — The nymphs first appear in early May and diapausing embryo according to the formula Y = are present until late July, with some eclosing earlier or later (0.847)(0.085)^, where Y is the diameter of the red spot and x is depending upon the weather. Eclosión begins at the time red the length of the embryo in millimeters. The spot disappeared by pine shoots begin elongating. Soon after, the pre-emergent the twelfth day. Giese and Wilson (1957) propose that the red nymph splits the egg chorion and then wriggles free. Though spot is absorbed by the embryo and supplies the red pigment of this process may take hours in the laboratory (Ewan 1961), in the nymphal abdomen. Red pigment accumulates in the lateral- the field the nymphs usually free themselves from the eggs in ventral region of the embryo's abdomen at the same time that less than 1 minute (Wilson and Kennedy 1974). Freed nymphs the red spot shrinks. immediately begin wandering over the bud surface and up and down nearby needles without pausing to dry out their exo- About 3 to 5 days before hatching, a bulge appears on the con- skeletons, as most other insects do. If humidity is high or the vex surface of the narrow end of the egg. This marks the expan- sky is overcast, the nymphs may spend several minutes on the sion of the egg-burster on the head of the pre-emergent first- tree. If it is a dry, sunny, and warm day, they vacate quickly. instar nymph. When fully expanded, the egg-burster splits the Most nymphs drop directly to the ground or are blown off by chorion of the egg. gusts of wind.

13 Nymphal eclosión occurs during a period of about 2 weeks. ground. While feeding, the nymphs withdraw plant juices and Each day new nymphs begin to appear around 6 a.m. Peak eclo- excrete liquid waste (through the anal pore). The waste is sión occurs between 8 and 9 a.m. and declines the rest of the pumped up with air to form the characteristic spittlemass (fig. day, culminating before 4 p.m. (fig. 13). Nymphs apparently do 14 and front cover). This froth prevents desiccation and prob- not emerge overnight (between 4 p.m. and 6 a.m.) (Wilson and ably fends off most natural enemies. Nymphs soon die if de- Kennedy 1974). About 33 percent of the nymphs hatch during prived of the spittle. Spittle averages more than 99 percent water the peak hour and about 85 percent hatch between 7 and 11 by weight and contains sugars and amino acids that are leftover a.m. On warm, sunny days nymphs emerge only during the 3 or metabolites. Bacteria may inhabit the sugary medium; sooty 4 hours of the early morning. On cool, cloudy, or misty days, mold will use it as a growth substrate. The pH of spittle ranges the daily emergence period is extended into the afternoon. from 7.1 to 7.8 (Wilson and Dorsey 1957).

Morning is the least stressful time for the primary eclosión of insects, such as young spittlebugs, that dry out quickly. Moisture certainly is important, but it appears not to be the only factor because the relative humidity often reaches 100 percent at night and also on rainy afternoons, periods when the insects do not normally eclose. Non-optimum temperatures may also squelch eclosión later in the day.

Nymphs iimnediately search out the alternate host plants when they reach the ground. They move quickly over small forbs and grasses. Ewan (1961) showed that newly emerged nymphs can travel long distances in just a few minutes in the laboratory. Moving onto suitable small alternate hosts, they feed singly or in groups at the root collars or in the axils of the lower whorls of herbaceous, rosette-shaped plants. On large plants, they feed at the root collar or occasionally from 2.0 to 5.0 cm above the

Figure ^ A—Spittlemass of Saratoga splttlebug nymphs.

The spittlemass of first-instar nymphs is only 3.0 to 4.0 mm across, but increases to about 13.0 mm as more spittle is added by the nymphs as they mature. Two or more nymphs on a single plant usually inhabit the same spittlemass. Average spittlemasses contain two or three nymphs, and large "community" masses—from 5.0 to 8.0 cm across—may contain from 10 to more than 50 nymphs of two or three different instars. Anderson (1947b) counted 40 and 51 first instars on two wild letmce plants and 25 and 30 on two asters.

Ewan (1961) estimated the average duration of the five nymphal stadia as 16, 7, 9, 10, and 15 days, respectively, or about 57 days for the entire growth period of an average nymph. Studies in the 1970's in Michigan indicate the average duration of the life of the average nymph as 53 days. Though these differ, one would expect slight differences from climatic, geographic, and 0500 0700 0900 1100 1300 1500 1700 annual variations. TIME (HOURS) Nymphs transform to adults outside the spittlemass on the stem Figure 13—Nymphal eclosión period of the Saratoga splttlebug. or leaf of the alternate host plant. Ecdysis has not been de-

14 scribed for the Saratoga spittlebug, but molting is similar for Nymphal density throughout pine stands differs greatly in space most cercopids. Doering (1931) and Severin (1950) observed the and time because of several variables. Eggs are on the trees, so following adult transformation of the closely related A. per- the numbers, size, species (mixtures), and distribution of the mutata Uhler. trees influence where nymphs will be at eclosión. Eggs, too, are highly aggregated (see fig. 12), which immediately causes the The mature nymph leaves the spittlemass, crawls up the stem, nymphs to be overdispersed right after eclosión. Taylor's power and firmly attaches its claws to the bark. By flexing its last ab- law index for nymphs is 1.42 (random = 1.00), indicating a dominal segment, it covers the lower surface of the abdomen moderate degree of aggregation (fig. 16). and thorax with spittle, which glues these segments to the stem. As the nymph bends its head and prothorax downward, the soft Most nymphs drop down from the trees, so first and second in- membrane adjoining them splits along the dorsomedial line. It stars are aggregated close to the trees. Wind carries some takes about 20 minutes for the insect to extricate itself; ñrst it nymphs a short distance from the trees, and nymphs on taller pushes the prothorax through the slit, then the head and the rest trees subjected to high winds during eclosión could be carried of the thorax follow, and finally the anterior abdomen emerges. long distances before settling on hosts. As nymphs age they The now callow adult bends backward and hangs down for move about and emigrate to the woodier alternate hosts. All of about a half hour while drying. When dry, the new adult bends these and other factors give the nymphs an uneven distribution forward, clings to the exuvium and disengages the tip of the ab- in a stand as a whole. In addition, in stands that have openings domen. The entire process begins at about 8 a.m. and is mostly or a low density of plants, or in areas where trees are more than complete by 10:30 a.m. 10 or 12 ft (3.0 or 3.6 m) apart, there is a population gradient spreading outward from each pine host. Ewan (1961) counted Because the ratio of woody plants such as sweetfern and late-instar nymphs on sweetfern in concentric rings around red brambles to other herbaceous forbs may be 1:4 or more in favor pine trees and found a decreasing gradient outward. The alter- of the latter, the nymphs understandably end up mostly on the nate hosts under the trees averaged more than five nymphs per forbs. As the nymphs age, however, they usually change alter- plant, whereas those 10 ft (3.0 m) away from the trees averaged nate hosts one or more times as their needs and the hosts' only one per plant (fig. 17). The gradient disappeared in denser suitability change. By the end of the third stadium, numerous stands having a thousand or more trees per acre when the nymphs have moved onto the woodier plants. Ewan (1961) distances between their crowns were less than 4 or 5 ft (1.2-1.5 reported finding at least 60 percent of the fifth-instar nymphs on m). The latter stands, however, are exceptions if infested by sweetfern and brambles during routine samplng of thousands of spittlebugs, because more appropriate alternate hosts tend to be acres of red pine stands. in the open. Spittlebugs ftirther open up the stand as they weaken and kill trees. A nymphal gradient also occurs in large Anderson (1947b) was first to note that nymphal density openings within a stand or along the edges of heavily infested decreased on most herbaceous plants and simultaneously in- stands. Anderson (1947b) counted nymphs on sweetfern plants creased on sweetfern as nymphs aged. On nine of the most com- from the edge of red and jack pine plantations out to 100 ft mon forbs, the number of nymphs per stem decreased from 1.5 (30.5 m) and obtained a curvilinear gradient (fig. 18). Addi- to 0.2 for first or fifth instars, respectively, whereas the tionally, he got similar results when counts were made in the sweetfern nymphal population increased from 0.3 to 5.0 for the vicinity of scattered large (12 to 16 in. or 0.3 to 0.4 m d.b.h.) same stages. jack and red pine.

More detailed studies later revealed that more than 80 percent of Wilson and Hobrla (in press) showed that the nymphs could be the nymphs start out on the forbs and remain on them sampled reliably for surveys if the ground was considered as a throughout the first and second stadia until early June. Emigra- uniform substrate. Using 0.1-milacre samples taken randomly, tion to sweetfern and brambles begins shortly thereafter and con- they were able to predict the mean number of nymphs from the tinues until late June—the approximate period of the third percentage of samples infested (fig. 19). stadium. From a study in 1956, Ewan (1961) noted that the nymphs on sweetfern and brambles averaged about 17 percent Adult stage—Adults begin to appear in late June or early on June 4 and 5, and about 50 percent on June 8 and 9, and July, and most have emerged by late July. Populations of adult about 80 percent at the end of June (fig. 15). This was a insects remain constant for a week or two and then decrease at a definite emigration from the herbaceous plants to the more rate of about 15 percent per week thereafter until late Sep- woody plants and not a differential mortality of plants or tember. Sometimes a few residual insects can be found in late nymphs because both the kinds of plants and numbers of October or until the first killing frost. nymphs remained stable throughout the month. The directed nature of this movement is particularly apparent when one con- In preparation for eclosión, the fully developed nymph climbs siders that sweetfern and brambles accounted for only about 14 onto a leaf of the alternate host and waits until its exoskeleton percent of the alternate hosts. splits. Ewan (1961) speculated that transformation probably oc- 100

if) X CL 60

UJ er LU CL

NYMPHS ON SWEETFERN 20 AND BRAMBLES

—1 r- 5 15 20 25 30 JUNE

Figure AS—Location and movements of Saratoga spittlebug nymphs during June. curred at night. Soon after drying, the newly formed adult flies Most sweep-net collections showed a preponderance of females, to the pine host and seeks out feeding sites. Copulation occurs but the whole-tree counts alone gave a sex ratio of 1.00:1.02 or within a few days, and the peak of egg laying 2 or 3 weeks nearly a 1:1 ratio. Sweep-netting probably biases the sex ratio later. slightly towards females because they spend some of their time ovipositing on the buds and are therefore more apt to be cap- At the beginning of adult transformation, males slightly out- tured than males. Ewan (1961) noted that in September the total number females, but within a few days the sex ratio approaches population drops to less than 10 percent of that in July and then 1:1. A collection of 1,088 adults taken in Wisconsin over 10 the females outnumber the males 2 to 1. weeks gave a sex ratio (female/male) of 1.00:1.12 (Ewan 1961). Anderson (1947b) sexed 3,100 adults from 18 separate collec- When the weather is favorable, the adults spend most of their tions to get a ratio of 1.00:1.18. I sampled adults in Michigan time feeding on the hosts' needle-bearing shoots. They nestle for 4 years by sweep-netting and whole-tree bagging and ob- down between the needles, facing outwards, and insert their tained the following sex ratios from 4,595 adults: mouthparts through the cortical tissue of the shoots and branches. They feed all over the tree, including the needle- Period Female/Male bearing portion of the mainstem, but prefer 1-year-old inter- mid-July 1.00:0.90 nodes in the upper crown. Once settled, adults may feed for late July 1.00:1.06 several hours, but if disturbed, they spring away and fly to a early August 1.00:0.92 mid-August 1.00:0.83 new host. Each adult makes from 2 to 5 feeding punctures each late August 1.00:0.81 day, with an average of about 2.6 per day (Ewan 1961). entire season 1.00:0.94 Feeding frequency peaks during late July and early August, 2.0 N = 72

2 L42 1.5- S = m o X

LU O 1-0 < er

0.5

I I I I I I I I I I I—I—r—I—I » I r 1 I—I—I > T I T I t I—I—I—r"T—I I I—I—I I I I I I I I « I I I I I I I I I « 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 MEAN

Figure ^ 6—Aggregation distribution of Saratoga spittlebug nymphs based on the relation between intertree variance (s^) and mean (m) number of spittlebug nymphs per 0.1-milacre sample. Dispersion index s2 = am ^ ^2 /g based on Taylor's power law. Equation s^ = m indicates a random relation. when each adult makes about 3.5 punctures per day. Mid- Host Damage September feeding generally drops to 1.5 punctures per day. The feeding puncture wound—Only adult spittlebugs Adults are active during the warmest days or parts of days. All damage pine. While feeding, the stylets of the adults' activity declines during cool and/or wet weather and nearly stops mouthparts enter and pass through the cells of the shoot cortex, at 15 °C. Consequently, there is little movement or feeding at penetrating to near the cambium. The stylets are narrow and night and in the cool of early morning. Adults are active only leave little evidence of a feeding puncture wound on the bark of during the warmest parts of the day in September and October. the shoot. Fresh punctures, however, can be detected if the They are easily hand collected when the temperature is at or shoot is inspected closely. The punctures can be traced in the in- below 15 °C. ner bark by a discoloration that delimits them. Occasionally, small resinous droplets may appear at the wound following Adult spittlebugs aggregate on trees to about the same degree as withdrawal of the stylets (Anderson 1947b). Light infestations of nymphs congregate on the alternate hosts. Taylor's power law as the spittlebug are difficult to detect, but heavy feeding occurring an index of aggregation gives 1.42 (1.00 = random), which is a over several seasons leaves the shoot surface uneven and lumpy. moderate aggregation and the same index as that for the nymphs This is particularly noticeable as the tree loses vigor. (fig. 20).

17 but the pitchy defect or scar remains permanently in the xylem CROWN PERIMETER as a small block to conduction. The defect also spreads up and down the shoot, leaving a dark streak up to 3.6 cm long in the co xylem (Kennedy and Wilson 1971) (fig. 22). er LU On repeatedly attacked trees, the injured cambium may not heal Ll_ I- over for two or more growing seasons. Slow healing leaves a LU LU pitch-filled necrotic streak that extends through two or more $ growth rings and terminates in a cuplike scar in the phloem (fig. CO 23A and B). These scars may be several millimeters across and oc LU are detectable externally as depressions and pitch-filled pockets Û_ in the bark. In trees nearing death, large scars contribute 10 to en X 20 percent of the injury to the current year's wood (Ewan CL 1961). >- Healed-over scars show considerable histological disruption. The 0 123456789 10 tracheids near the scar are malformed, and xylem cells just DISTANCE FROM TREE STEM (FEET) beneath the affected cambium are arranged with their long axes in a circumferential plane (fig. 23D) rather than in the normal Figure M^Density of Saratoga spittlebug nymphs relative to plane parallel to the shoots' long axes (fig. 23C). Each scar, ex- distance from pine tree. clusive of surrounding abnormal tracheids, blocks from 1 to 5 percent of the conductive area of the xylem (Ewan 1961).

CO X CL Necrosis of the cortical tissues following feeding is apparently ^ 90 >- due to a heat-labile substance—probably an enzyme contained in 2 X «°- the spittlebug's salivary glands. Micro-organisms are probably 1- not responsible for the tissue necrosis and scar formation, even ^ 70. though the spittlebug may transmit burn blight disease, which is Q UJ caused by the fungus Chilonectria cucurbitula (Curr.) Sacc. h- 60- (D (Gruenhagen and others 1947). ÜJ ^L«- .n50- ;^ Feeding wounds occur in a definite horizontal gradient on both è '*°" red and jack pine trees. Ewan (1953) showed that the spittlebug LJJ LL prefers feeding on the first internode and its preference 1- 30- • UJ decreases down the stem and inward toward the stem on red UJ ^ 20- \^^ pine branches (fig. 24). This excludes the leader and current (n • • >Vs^ • \- growth shoots, which always have the lowest wound densities. -Z. 10- LÜ •^*- • • The gradient is consistent throughout the crown at any branch O er • "~ ^- ~~ level and holds true at all feeding densities. Anderson (1947a) noted a similar gradient for jack pine, but proportionately more DISTANCE FROM PINE PLANTATION (FEET) feeding wounds were found on the current growth compared to red pine. Figure 18~De/7s/iy of Saratoga spittlebug nymphs on sweetfern relative to distance from an infested pine plantation. There is practically no vertical gradient between branch whorls on the upper to lower portion of red or jack pine trees. That is, feeding wound counts on any internode on the upper crown are The feeding puncture shows no immediate evidence of injury in nearly the same on a comparable internode lower on the tree the shoot, but about 17 hours later a slight tannish discoloration (fig. 24). Also, feeding wound densities are the same between appears at the cambial-xylem interface (Ewan 1961). During the the top and bottom surfaces of the branches. However, from 25 next few days this area darkens and broadens into a reddish and to 40 percent more feeding injury is visible in the phloem than somewhat squarish blotch from 3.0 to 4.0 nmi across. Close ex- on the xylem surface, and the percentages generally increase on amination shows the blotch as a resin-filled pocket of necrotic progressively older growth (Ewan 1953). tissues in the phloem and cambium (fig. 21 and front cover). As the shoot continues growing, a disruptive pitchy area develops in Physical injury—Early injury is entirely hidden from view, so the xylem adjacent to the injured cambium. Still later, the injury that subclinical or subeconomic damage to the tree cannot be is gradually repaired by proliferation from healthy cells nearby, easily assessed at any time during a spittlebug infestation. When

18 o 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0,8 0.9 .0 PROPORTION INFESTED

Figure 19—Mear? number of spittlebug nymphs per 0.1-milacre sample predicted by percentage of samples infested. Values of n are confidence bands for sample sizes.

flagging and other gross symptoms of injury become obvious, of weak trees grow in the same proportion to those of more the threshold of economic injury has been surpassed. Gross in- vigorous trees. Hence, if the length of the lateral growth is com- jury may occur in only 2 years when a spittlebug population pared to the length of the terminal growth for the same year rises rapidly. A spittlebug population, however, may build up (L/T ratio) for each branch whorl on the crown, and then these slowly over several years so that injury remains less obvious. ratios are plotted on a graph, a normal tree will show an in- One early indication of subeconomic injury is a growth change clined or sloped growth pattern (ñg. 25). Spittlebug-injured in terminal and lateral shoot elongation (Benjamin and others shoots are far short of their potential length. When plotted, the 1953). Growth, of course, can be shortened by many adverse or L/T ratios for injured trees will produce a nearly horizontal climatological factors such as poor soil, drought, etc., but then growth pattern (fig. 25). This pattern then indicates evidence of growth is shortened for all trees in the stand. That is, the shoots subthreshold spittlebug injury.

19 MEAN Figure 20—Aggregation distribution of Saratoga spittlebug adults based on the relation between intertree variance (s^) and mean (m) number of spittlebug adults per tree. Dispersion index s^ = 3011*2 is based on Taylor's power law. Equation s^ = m indicates a random relation.

Figure 2A—Adult spittlebug feeding puncture wounds on wood of Figure 22—Two adult spittlebug feeding scars showing pine shoot. longitudinal streaking in the xylem.

20 1 app^H*' ■ ^^^"ii^^^^^^^B ^r P '■" ■ 1 ÄJL-N_. -*'».^

1^ '^1

^H^'%

\ h ÉÉ Figure1 23— Adult spittlebug■ feeding scars: A—Pitch-filled pockets. B—Cross-section of sfioot. C—Normal sfioot tissue. D—Histological disruption of shoot from feeding injury.

21 5 wounds and scars. Extensive feeding kills branches, the tops of LEADER JÊÊ THIRD trees, and eventually the whole tree (see cover). Surviving trees 4 AND BOLE are stunted and have crooked boles with distorted branches and 3 shoots (Lyons 1952, Heyd 1978) (fig. 26).

2 Sapling pines are more vulnerable to spittlebug injury, but even UJ û I pole-size trees may be injured because heavy populations kill O and stunt trees, thereby maintaining openings for alternate hosts. g o Heyd (1978) examined a 45-year-old red pine plantation that was LU CURRENT FOURTH still being attacked by spittlebugs where there were dense t 4 WHORL ^^ WHORL i sweetfern patches. These injured trees averaged 7 m tall and had sweep, crook, forks, and large and extensive lower limbs. They greatly exceeded tolerance for utility poles, lumber, or other products (Guilkey 1958), and harvesting them for pulpwood O would have been difficult because of loading, hauling, and chip- Ö CO ping problems. Other trees averaged 11m tall and were free er ■ from deformities. They had been attacked years earlier, but had UJ FIRST FIFTH crowded out the alternate hosts when their crowns closed. Û_ WHORL ^^ WHORL co LU Crooks and sweep of the injured trees resulted from stem (T Z) necrosis and lower whorl dominance. Added to this, the snow h-o load compounded the amount of sweep and internal defects. ;z Z) Slices of the bole showed extensive damage in the wood and CL much compensatory lateral growth. Scars from numerous O J wounds left stained, resin-soaked areas that degraded and struc- SECOND SIXTH turally weakened the wood (fig. 27). Û WHORL WHORL LÜ UJ Physiological /n/ury—Internal stresses and chemical im- balances result from spittlebug feeding in two ways: the adult withdraws plant juice, and the necrotic resin-filled feeding scars block water conduction.

-'—""^—1 1 1 1 2 3 4 2 3 5 6 During a single feeding the adult withdraws about 0.4 cm^ of plant juice (Anderson 1947a). Considering that moisture content INTERNODE AGE (YEARS) of the bark and phloem ranges between 208 and 221 percent of Figure 24—Distribution of Saratoga spittlebug feeding-puncture the dry weight and the inner bark is 1.0 to 2.0 mm thick, the wounds on red pine tree by leader and whorls. amount of liquid removed at each feeding equals the moisture in about 3.0 to 6.0 cm^ of inner bark. If moisture is not replaced, a shoot rapidly dries out and dies. Ewan (1961), however, The L/T ratio, however, is unreliable as an indicator of showed that the liquid is replaced by rapid conduction im- subeconomic injury following rapid population buildup because mediately after feeding. Even heavy feeding injury is not evident there is a 1-year lag between effects on the tree and adult right after feeding, but water conduction diminishes throughout feeding damage. Shoot elongation is complete by the time the the season as necrosis increases and vessels are blocked with spittlebug feeds, and the feeding injury will not affect the resin, a condition that finally reaches a threshold where there is growth until the following season. Shoot flagging would then oc- irreversible moisture deficiency. Anderson (1947a) showed that cur simultaneously with the change in L/T ratios, so the ratios the effect of a feeding injury on water content of the shoot was would be of little value. an inverse linear relation for jack pine (fig. 28). Heavily injured red pine shoots begin yellowing when their moisture content Heavy feeding for a year or two, or prolonged light to moderate drops to about 79 percent of normal—the permanent wilting feeding for several years, eventually takes its toll. Shoots pro- point (Marshall 1931). Anderson (1947a) also showed that as the gressively shorten and then the tips of branches and the tops of number of feeding punctures rises, water conduction drops trees turn yellow and finally red (flag). Flagging is generally drastically. Jack pine shoots with about 12 punctures/cm^ con- more pronounced on the tree tops but may occur anywhere on ducted only one-thirtieth as much water as similar shoots with the tree. Branches twist and the bark of shoots becomes bumpy less than two punctures. Shoots with more than 15 punc- due to uneven healing and scarring from the feeding puncture tures/cm^ were unable to conduct water.

22 LO

0.9 INJURED TREE

0.8 Y = .6I3-.008X er 0.7

0.6-1 er ÜJ 0.5

< 0.4 er UJ NORMAL TREE Y = .73I-.093X 0.2

0.1

0 2 3 4 BRANCH WHORL

Figure 25—Lateral-terminal elongation growth pattern for normal sapling red pine shoots and shoots responding to Saratoga spittlebug injury.

As pine shoots deteriorate from necrosis, the carbohydrate con- population. Equally important is the number of trees in the tent changes. Moderately infested trees have only about 25 per- stand, for the damage potential of a given insect population cent of the usual amount of sucrose in the phloem. Roots of the depends on tree density, so that fewer trees are damaged more. same trees have at least 30 percent less reducing sugars (Ewan 1961). This type of response by the tree is a typical result of a Therefore, in order for the degree of tree damage that will result plugging of the xylem vessels followed by a shortage of water in a stand from a particular spittlebug population to be and reduced food production in the foliage. understood, the stand must be viewed as a whole, as a quan- titative expression of tree size and density. The total length of Stand damage—Spittlebugs routinely kill or ruin large por- needle-bearing branches on each tree provides an accurate ex- tions of pine stands, especially if trees are less than 5 m (16 ft) pression of tree size, but such measurements are too time- tall. Some stands, however, remain apparently uninjured even consuming. The product of tree height and number of branch when spittlebugs appear to be abundant. Various factors of the whorls is easier to measure and correlates so closely to length of stand profile are largely responsible for these differences. needle-bearing branches that it can be used instead (fig. 29).

Damage to a young pine stand or plantation, of course, depends An excellent expression of the total amount of spittlebug "food" primarily on the number of feeding adult spittlebugs. But tree in a stand is called tree-units—an index calculated from the size, too, is important in assessing or predicting damage because product of mean tree height (in feet), the mean number of spittlebug-susceptible pines may differ in size by a factor of five branch whorls, and the mean number of trees per unit area or more. A doubling in tree height results in at least a tripling (usually an acre). Because most northern pines are symmetrical of the amount of foliage. Thus, the smaller the tree, the more uninodal trees and often planted in rows, they easily lend rapid and severe will be the damage from a given spittlebug themselves to the tree-unit index. A typical index, for example,

23 f im.. ^^ ' * m ^

■if

'>"■■"%'' '»^^^JBmtf^^^^BÊ^^^^^^wl^^mmif '^ i^^% ^

Figure 26—Even-age sapling red pines distorted from Saratoga spittlebug feeding. A—Stunted and deformed tree in sweetfern pocl^et. B—Tree forl

24 Figure 27—Sapling red pine boies showing internai injury from aduit spittiebug feeding. A—Crool

25 How many and what kinds of alternate hosts, then, are needed to support a damaging spittlebug population? Ewan (1961) indicated that epidemic populations occur in areas with 60 or more alternate hosts per milacre, but the presence of sweetfern and other woody plants enhanced the probability of an epidemic. Kennedy and Wilson (1971) showed that sweetfern was actually the only alternate host crucial for population build-up when alternate hosts were scarce. Numerous other woody and herbaceous alternate hosts, however, could support a high spittlebug population, even if sweetfern is absent.

Sweetfern must occupy from 35 to 40 percent of the ground, in lieu of other hosts, to produce spittlebug populations capable of inflicting moderate and heavy damage, respectively (Kennedy and Wilson 1971) (table 5). If sweetfern is absent, other host plants must occupy from 50 to 80 percent of the ground to 5 10 15 20 obtain populations capable of the same damage levels. Sweetfern MEAN NUMBER OF FEEDING PUNCTURES PER CM ^ is thus twice as important as other plants as a component of infestations. Outbreaks without sweetfern apparently are rare Figure 28—Dens/iy of Saratoga spittlebug feeding-puncture because the ground must be lush with other host plants. wounds relative to moisture content of jack pine slioots. Sweetfern alone may occupy from 0 to 60 percent of the ground in a planting, but more often sweetfem is combined with other for a well-grown dense plantation of red pine might be 36,000 host plants. tree-units per acre, based on trees 6 ft (1.8 m) tall with 6 branch whorls and 1,000 trees per acre. In contrast, a younger, Wilson and others (1977) showed that 63 out of 91 spittlebug poorly stocked stand having trees 3 ft (1 m) tall with 4 branch research areas contained some sweetfem, and sweetfern occupied whorls and 300 trees per acre would have only 3,600 tree-units an average of 21 percent of the ground on the areas. However, and thus be 10 times more vulnerable to injury by a spittlebug blueberry and other tme altemate hosts occupied an average of population of equal size. 24 percent of the ground and interim altemate hosts averaged another 17 percent. Thus, the average planting with this com- Density of alternate host plants ftirther determines whether a bination has more than enough plants for potential heavy spittlebug population is capable of increasing sufficiently to damage. cause moderate or heavy injury. Kennedy and Wilson (1971) clearly showed that spittlebug injury increased directly as density of suitable understory vegetation increased (fig. 30). This ex- cluded mosses, lichens, and grasses, which are nonhosts. A stand with sparse or unsuitable understory vegetation will never be injured by the spittlebug, no matter what its size. Alternate host density must be at least "sparse-medium" before moderate injury occurs and more than "medium-dense" for heavy injury. Table 5—Approximate percentage ground cover occupied by sweetfern and other alternate host plants needed to produce Ewan (1961) listed several factors responsible for favoring moderate and heavy damage by the Saratoga spittlebug development of abundant alternate hosts: Alternate host Ground cover (o/o) • Absence of trees in rocky or stumpy spots or other places considered undesirable for planting. Moderate damage^ • Uneven planting so that areas even as small as 0.04 ha may Sweetfern 0 10 20 30 35 be considered as fiiUy stocked but still contain openings of 4 Other plants 50 40 20 5 0 m^ (3.4 sq yd) or more. Total 50 50 40 35 35 • Failure of trees in localized areas due to various biotic and Heavy damagez Sweetfern 0 10 20 30 40 climatic factors in the early life of the plantation. Other plants 80 70 30 10 0 • The spittlebug itself, which stunts or kills the young trees Total 80 80 50 40 40 and thereby creates its own opening. In addition, sweetfem competes best on sandy sites—sites where 1 Moderate damage means pines show stunted growth, some crooked boles, and light pines are often planted and thus may be under stress from insuf- flagging. ^Heavy damage means pines show crooked stems and branches, heavy flagging, top ficient site requirements. kill, and mortality.

26 no-

100 ÜJ

(/) 90 Lu X 80 < er ÛÛ 70 o 7^ fío Ul < III ÛD bO ÜJ -I 40 Û N= 104 ÜJ Y= 2.729+1.145 X ÜJ r = 0.954 Z 30 ü_ O 20 X h-co 2 lU ÜJ

10 20 30 40 50 60 70 80 TREE HEIGHT (FEET) X WHORLS

Figure 29—Tree height x whorls as an index of length of red pine needle-bearing branches.

More than one-third of the ground in an average planting is covered by such nonhost plants as grasses and sedges. At best, these could provide shelter; more likely, they hinder nymphal X LiJ sojourns between host plants. Nymphs forced to vacate interim Q host plants must find other interim hosts or true host plants to >- survive. While searching, they must encounter many nonhost £r plants. Thus, the higher the proportion of interim hosts and nonhosts relative to true hosts (especially sweetfem), the less chance for survival. Small nymphs likely should have the most < difficulty surviving the rigors of host change when many ÜJ nonhosts are available to hinder them. Young nymphs do not move about much or over long distances, probably because of these obstructions. Older nymphs wander more and tend to

S^IR^S^E SPARSE SPARSE ^,,„^ MEDIUM ,,,3, VERV^ vacate both true and interim hosts in favor of sweetfern and, if present, willow. DENSITY OF UNDERSTORY VEGETATION Figure 30—Injury from Saratoga spittlebug relative to density of Though adult counts are the only sure indicators of host damage, understory vegetation. nymphal counts (in fourth and fifth instars) correlate closely

27 with adult injury and, therefore, can be used instead. Nymphal counts have distinct advantages because nymphs can be Í2 estimated more easily and more accurately than the adults, and < O counting nymphs permits sufficient time to prepare for control if C/) needed. Plotting nymphs per tree-unit against adult feeding scar O 40 counts on red pine gives a highly significant linear relation (fig. 31). Thus, by knowing the number of tree-units in a red pine Lü U- plantation, it is possible to predict the subsequent amount of tree LJ_ damage from the nymphal population (Ewan 1958b). O cr Lü m Ewan (1961) reported that if infested trees exhibit 35 or more feeding scars per 4 in (10.1 cm) of 2-year-old internodes, shoot mortality and growth deterioration will generally occur the following year or two. An average of just over one nymph per tree-unit results in 35 adult feeding scars per 4 in (10.1 cm) of shoot (figure 31). The following formula derived from this NYMPHS PER TREE-UNIT figure can be used to estimate the number of feeding scars from the nymphal population in an infested red pine plantation: X = Figure 31—Saratoga spittlebug nymphs per tree-unit as a predic- 31.3 a/b, where X is the number of feeding scars, a is the mean tor of adult feeding scar density. Feedings scars are expressed as number of nymphs per 0.1 milacre, and b is the number of tree- the number per 4-inch section of the 2-year-old internode. units per 0.1 milacre.

28 Population Ecology, Dynamics, and Control

The outcome of spittlebug injury depends on various interactions Sweetfern competition stresses pines, apparently through of the spittlebug, the tree, the ahernate host, and the physical moisture depletion (fig. 32). During dry summer periods, soil environment. The following ecological and population dynamics moisture is least in sweetfern-covered soils. And after heavy models show these various interactions in a sequential arrange- rains, soil water content drops fastest where there is sweetfern. ment with the physical effects on the stand as the final result or The reverse is true for blackberry-covered soil. That is, outcome. Natural influences can and do modify the degree of sweetfern, blackberry, and grass use soil moisture at different variation of the components and are thus the factors in the rates. Moisture stress can be especially critical on the lightly overall change of the stand. This statement implies that the podsolized sands that are highly suitable for sweetfern, and major or key influences can be manipulated in favor of ap- where red and jack pine are usually planted (Wilde 1946, propriate forestry management practices. Rudolph 1950).

Ecological Model Sweetfern is a nitrogen-fixing plant (Ziegler and Huser 1963) and in small clumps may be beneficial to pines. However, The ground cover association—the kinds and numbers of alter- where sweetfern is abundant, trees are much smaller, less nate hosts present—determines the extent of injury to the tree numerous, and, therefore, highly susceptible to injury. Crown because of its affect on both nymphal survival and tree growth closure, which shades out sweetfern, takes much longer or may (fig. 32). Alternate hosts are obligatory to the insect, and not occur at all. sweetfern in particular is important for high spittlebug survival levels. Blackberry (Rubus spp.) and other ground cover plants Sweetfern may add to the stress of the tree when red or jack are excellent alternate hosts; others are interim host plants, pine becomes infected with sweetfern blister rust, Cronartium useful for only a portion of the nymphal period; and still others, comptoniae Arth. This rust uses sweetfern for an alternate host such as grasses, are nonhosts. Greater density of the favorable and is often fatal to pine seedlings or causes defects in saplings nymphal hosts not only means a greater spittlebug population (Anderson 1963). Jack pine is the preferred host (Anderson and potential but also greater competition for soil moisture. Trees in French 1964). the vicinity of sweetfern, even if spittlebug is absent, are shorter—their heights being in direct proportion to the density of The surviving nymphal populafion determines the numbers of the sweetfern. This is true for various age stands, and the effect adults, and in turn adults provide the egg population that is exerted in the same year of planfing and thereafter (Clements becomes the new nymphal population the following year. Each and others 1968). More seedlings die when planted in sweetfern of these life stages has its own regulating determinants, which pockets than in sod or blackberry patches. In strawberry will be discussed under the insect-tree population dynamics patches, trees grow above average in height. submodel.

SHADING AND STAND CLOSURE

LOW-MODERATE VOLUME LOSS LIMBINESS,CROOKS PARTIAL BR. FLAGGING

MODERATE TRANSPORT VOLUME LOSS BLOCKED WHOLE BRANCH FLAGGING TOP KILL QNOUNO ADULT FEEOtNG COVER FEEDING SCAR ASSOCIATION EXPOSURE DENSITY

TISSUE HIGH VOL LOSS NECROSIS TOP KILL, DEGRADE TREE MORTALITY

TREE SIZE AND DENSITY

SWEEP AND BREAK

INSECT-TREE DYNAMICS VULNERABLE TO SNOW DAMAGE

Figure Z2—Ecological model of the Saratoga spittlebug.

29 The number of insects reaching adulthood determines the degree pathogenicity and subsequent decline of the tree. Several of feeding. Considering that each adult makes more than two Aphrophora species are vectors of viruses such as Pierce's feeding punctures each day when the temperature is above 60 °F disease on grape and alfalfa, and A. saratogensis may transmit and that each may live 2 months or longer, it only takes a few viruses but there is no record of such transmission at this time. adults to injure small trees. Injury, however, is relative and also depends on the amount of feeding surface available. That is, tree Population Dynamics l\/lodel size and density are important and may vary in a stand by a factor of 10 or more. Small trees widely spaced are most Numerous natural factors interact within the ecosystem to vulnerable to injury because of the small feeding surface or modify a spittlebug population, and when they are minimal, out- tree-units. breaks ensue. Sometimes we are able to manipulate these variables and thus reduce spittlebug populations before in- Feeding puncture wounds form resin-filled scars that block water tolerable damage occurs. The major agents of this ever-changing transport and cause moisture stress at various locations within system can be shown through a spittlebug-pine population the trees but especially in the upper crown where feeding is con- dynamics model (fig. 33), which is a submodel of the population centrated (fig. 32). Seasonal rains, drought, and the water- ecology model (fig. 32). holding capacity of the soil further contribute to the amount of moisture stress. Stressed trees grow short shoots and short The spittlebug egg—from the moment it is laid, through its long needles, reducing photosynthetic potential. Stunted shoots yield dormant period, and until the nymph hatches in spring—is af- smaller buds, which produce still shorter shoots in the year fected by physical and biological agents that threaten its survival following. Small buds, on red pine at least, influence the (fig. 33). For example, Milliron (1947a, 1947b) reared two oviposition pattern so that more eggs are laid on the top of the parasitic wasps from spittlebug eggs. One of these, Ooctonus tree, at least until the top dies and stops forming buds. Stressed aphrophorae Milliron, is a mymarid, and it parasitized between trees also synthesize inadequate carbohydrates and therefore pro- 8.5 and 9.3 percent of eggs collected from two pine stands in duce less wood fiber. September. Soon after parasitization, spittlebug eggs turn a dull whitish pink or lavender and the red spots vanish. Gradually the Lightly stressed trees show only little volume loss, light branch eggs turn gray-blue to blue-black and finally black. The eggs are flagging, slight crooking, and a slight preponderance of exceptionally turgid, somewhat distorted, and appear larger than limbiness in later years. Caught early enough, spittlebug control normal. Adult wasps issue through a small hole in the end of on such trees will cause a rapid response and recovery. More the egg between early September and mid-October. stress, though, will yield considerably more damage and volume loss. Feeding injury then coalesces and subsequently blocks so The other wasp, Tumidiscapus cercopiphagus Milliron, is an much of the transport tissues that branches and tree tops die. aphelinid. Milliron (1947b) reared one or two adults from the Spittlebug control at this level should only be decided from the eggs, and in one instance he watched a male and female escape economic value and the management criteria planned for the from the same egg. The adults emerged in October from eggs stand. Conversions to other uses may be more valuable than collected in September. The parasitized egg is turgid and shiny direct insect control, if management plans will permit. High black. Ewan (1961) reared T. cercopiphagus and recorded 3 and moisture stress is severely damaging to the trees and manifests 5 percent parasitization from eggs collected in March. The as very high volume loss, severe degrade, and mortality. Con- parasite adults emerged 3 to 4 weeks after the spittlebug nymphs trol of the insect at this level of injury is almost always imprac- began emerging in the laboratory. tical. Such stands should either be replanted and managed for spittlebug, left for wildlife, or converted to other uses. Egg predators are either rare or illusive. I have noticed large red mites on the eggs in spring but have never observed them An additional effect of feeding occurs where the bole is heavily feeding. Prolonged exposure to cold temperature is required for scarred and necrosis is rampant. Large dead areas in the wood stimulating diapause release. Ewan (1961) found that 1 week at cause the tree to compensate by growing on the opposite side of -18 °C was insufficient for hatching but 2 months at -7 °C the stem. This often produces structurally weakened wood that prompted normal emergence. Death of the eggs from cold is may break over from external stresses. Moderately and heavily unlikely because exposures far below freezing are common in damaged trees and those with inordinate sweep or crooking northern pine stands. We have collected eggs following over- break or bend readily from snow. night temperatures of -32 °C with no apparent decrease in hatching. Additional stresses on the tree, of course, can occur from various insect pests and disease pathogens partial to pines. Bum Some eggs die during winter nevertheless. Some eggs may be blight fungus has been isolated from the necrotic areas around infertile, and sometimes more than 50 percent do not hatch. the spittlebug feeding puncture. Its role is uncertain as to Moisture may be involved, especially in the spring just prior to

30 MOISTURE MOISTURE TEMPERATURE

EGG NYMPH,

LOW 1 SPITTLEBUG TEMP DYNAMICS

EGG No - Nc PARASITES PREDATORS MIGRATION

IN: TOUT

PREDATORS PARASITES ADULT —^ DISEASES

. ^ - ^ 1 SMALL LARGE 1 ALTERNATE SAPLING SAPLING 1 HOSTS 1 INSECTS DISEASES TREE ETC. DYNAMICS ' '

SEEDLING POLE + ^ W MATURE

Figure 33—Population dynamics model of the Saratoga spittlebug-pine ecosystem. W = winter, S = seed, N2-N5 = second to fifth nymphal instars. hatching. Eggs collected and placed at 76 percent relative cent RH (fig. 34) but will succumb in less than 12 hours at 30 humidity (RH) did not hatch in the laboratory, while others percent RH (Ewan 1961). Nymphs reared on potted plants in the placed at 100 percent RH did. laboratory die within 24 hours even if forming spittle unless plastic bags cover the plants. In the field, humidity is generally Wind may influence the survival of some eggs and thus the high at hatching so that nymphs usually are able to cover subsequent survival of the nymphs. The drying of bud scales themselves with spittle before desiccating. Spittlebugs hatch in and the expanding of shoots in spring loosen the eggs, which the early morning hours, and thus can take advantage of cool sometimes fall from or are blown from the tree. Once on the temperature and high humidity—the best conditions for low ground they may be more readily preyed upon by ants or other évapotranspiration rate. Newly hatched nymphs seldom remain insects. Eggs may be blown some distance from the alternate on the trees for more than a few minutes, favoring the ground hosts, causing the emerging nymphs to be unable to find food. where the humidity is higher (Wilson and Kennedy 1974). Once they are on the ground, the nymphs' immediate survival depends Moisture is a critical limiting factor for the young nymphs. Soon upon the proximity of suitable local humidity during the day. after hatching they must find an alternate host and cover The humidity near the ground, especially under a tree, is higher themselves with spittle. Under laboratory conditions some newly than on the tree, and the rapid movements of searching nymphs hatched unfed nymphs will live 2 to 3 days if kept at 100 per- normally can bring them to a host within a few minutes (Ewan 1961).

31 100

1007o R.H. (N = 229)

24 36 48 72 HOURS OF EXPOSURE

Figure 34—Survival of newly hatched Saratoga spittlebug nymphs when exposed to 30 and 100 percent relative humidity.

Late spring frost shortly after hatching is another critical factor Anderson also tested unadapted third-instar nymphs to momen- affecting nymphal survival (Ewan 1958a). For example, in mid- tary exposure to freezing and subfreezing temperatures in the May 1957, temperatures dropped to between -9 and -5 °C in laboratory. He recorded no mortality at 0 °C, 50 percent at -2 upper Wisconsin and adjacent Michigan. Most nymphs were in °C, 75 percent at -5 °C, and 100 percent at -7 °C. Precondi- the first instar and just forming spittle. The cold air penetrated tioning the nymphs at 0 °C for 12 hours reduced mortality but the duff and destroyed about 85 percent of the population did not lower the minimum at which 100 percent mortality throughout red pine stands in the area. Similar stands further occurred. south lost less than 10 percent of the nymphal population; temperatures there had dropped to only -2 to -1 °C during the Subfreezing temperatures seldom affect the fourth and fifth in- same period. Secrest (1944) noted a similar occurrence in 1942, stars because they appear in late June. Secrest (1944), however, in central Michigan. The nymphal population dropped con- tested fifth instars to determine their resistance to cold. At siderably following a frost in early May when temperatures various temperatures and exposure times he found the following dropped to between —9 and -6 °C. Events such as this usually values: occur when the late frost is preceded by a week or more of 21 to 27 °C temperatures, which provide abundant day-degrees for spittlebug hatching. Temperature (°C) Exposure (hr) Mortality (percent) -6 to -5 2 60 Anderson (1947b) logged mortality of third-instar nymphs in the -4 to -3 2 77 field when temperatures dropped to —2 °C and remained below -8 to -2 2 89 0 °C for 7 hours. About 80 percent of the nymphs died if their -9 to -2 2 89 spittlemasses were above the duff. All nymphs protected by the -9 to -8 1 100 duff, where the temperature dropped to only 2 °C, survived. -7 to -3 18 100

32 First- and second-instar nymphs can die during very hot, dry the pine stand. Although spittlebug adults are not strong fliers, weather, especially in open stands with sparse ground cover that they must move about a great deal, for nearly every pine stand insufficientiy protects the nymphs. Many nymphs died in mid- contains some Saratoga spittlebugs. Immigration and emigration June 1956 in northern Wisconsin, when daytime temperatures can certainly influence the ultimate population in a stand. Spit- for 4 days soared to 32 °C and above—far higher than normal tiebug movement is probably the most critical when new stands for that time of year. Subsequently, the humidity fell to critical are planted near old infested ones or when they are planted levels in the open, drying up the small spittlemasses and the among old brood trees from which the insects move onto the nymphs too. In two open-grown red pine plantations, nymphal new trees. populations in open, sunny locations dropped between 63 and 70 percent because of the hot spell. In contrast, nymphal popula- The adult is commonly parasitized by Verrallia virginica Banks tions protected by heavy shade dropped only between 16 and 32 (Thompson 1977). Linnane and Osgood (1977) were the first to percent (Ewan 1961). Linnane and Osgood (1976a) similarly rear this adult parasite from the Saratoga spittlebug in Maine. recorded more than 60 percent reduction of third and fourth in- This pipunculid parasitizes the callow adult during the second stars in Maine in June 1975, following 2 days with temperatures week of July. It has two instars—the first instar appears by mid- exceeding 32 °C and several days without rain. Hot, dry July, the second by the end of July. Larval development takes weather seldom occurs during the first or second nymphal from 6 to 7 weeks, and all parasites have vacated their hosts by stadia, and most young pine stands susceptible to spittlebug have the first week in September. Parasite pupae overwinter on the dense undergrowth that protects young nymphs against drying. ground (Linnane and Osgood 1977). Emergence coincides with spittlebug adulthood in early July. Most fourth- and fifth-instar nymphs are less susceptible to drying. When nymphs are deliberately removed from spittlemasses Ewan (1961) probably collected the same species in Wisconsin, and placed on the ground in full sunlight on hot days, they though he failed to rear adults for positive identification. quickly seek hosts and reestablish themselves without difficulty. Parasitism sometimes exceeded 60 percent in some years and High temperatures during molting probably injure the nymphs locations. Consequently, he noted that areas of high parasitism more than at other times. showed large population declines the following year.

Predators certainly take their toll of nymphs, but records are Most parasitized adults have one parasite larva, but some have scanty. The nymphs are probably attacked more often while more. Two male spittlebugs each had four parasites. It is dif- moving among plants than when in the spittlemass. Secrest ficult to imagine a parasite ftilly developing when two or more (1944) notes that several predators, including reduviids, sphecid inhabit one insect because a single full-size second-instar larva wasps, pentatomids, damsel bugs, and spiders, have been almost fills the entire spittlebug abdomen. In fact, the abdomen observed capturing the sympatric pine spittlebug. Similar often appears distended from only one large parasite. In early organisms certainly feed on the Saratoga spittlebug as well. stages of parasitism, first-instar larvae were frequently found in Knull (1932) reported a parasitic fungus, Entomophthora spittlebugs that had functional gonads. Whittaker (1969) reports aphrophora E. Rostr., that was highly destructive to the pine that some parasitized cercopids are still able to lay a small com- spittlebug and might also be an enemy of the Saratoga spit- plement of eggs (4 rather than 30) before the second-instar lar- tlebug. Anderson (1947b) found a few mummified Saratoga spit- vae appear. By then the abdominal contents become atrophied, debug nymphs but did not identify the pathogen. and the reproductive organs are the first to degenerate. Parasi- tized adults appear unhampered in their movements and still may Nymphal parasites are unknown. Drosophila azteca (Sturtevant copulate, though the abdomens are distended and the internal and Dobzhansky) inhabits spittlemasses of the similar reproductive organs of one or both are gone. Aphrophora canadensis Walley but its role is unknown. It could be parasitic because the closely related fly Clastopteromyia in- There are few records of other spittlebug parasites. Anderson versa (Walker) (= Drosophila inversa Walker) is an ectoparasite (1947b) and Linnane and Osgood (1977) reared a few unknown of Clastoptera spittlebugs (Kelson 1964). specimens.

Migrations or movements between alternate hosts can variously Various organisms prey on spittlebugs. Spiders, especially the affect nymphal survival. At such times nymphs are not only jumping species (Salticidae) and crab spiders (Thomisidae), cap- vulnerable to natural enemies but also to hostile environments. ture the adults. Adults sometimes fly into spider webs, and ants Hot, dry weather has the least effect on the larger nymphs, drag away spittlebugs. A large red mite frequently adheres to which do most of the moving. Distances between suitable hosts the adult in late August and September, but it probably is not could be critical. important because most eggs are laid by then (Ewan 1961).

The adult stage, of course, is the stage that influences the tree, Dead adults are often infected with fungi of the genus so that every factor that lowers adult survival indirectly affects Beauveria, which has a long list of insect hosts.

33 Mortality factors for the entire generation of the spittlebug are the shoots, makes them more susceptible to the fungus. Burn best understood in the form of a life table. The life table pro- blight has not developed in stands where the spittlebug has been vides progressive mortality for each stage of the insect by iden- controlled. Over the years, the spittlebug has changed preference tifiable factors—such as parasites, predators, temperature, etc.— from jack pine to red pine because of planting practices. Since that greatly reduce the population of each generation. Table 6 then burn blight has not been a problem, probably because it is presents a spittlebug life table for 15 generations and varying only weakly pathogenic to red pine. Nevertheless, this situation population levels from light to heavy. The data for the life tables could change as new strains develop and the tree's tolerance is were taken in Michigan in the mid-1970's. The ranges of per- overcome. cent mortality in the last column of the table show the variation of the mortality for the major factors observed. Note particularly The health of the tree further influences its survival and its that parasitism was only from 1.6 to 11.9 percent, which is far tolerance to the spittlebug and transmitted pathogens. Pines are less than the 60 percent observed by Ewan (1961) in some hosts of many other insects and diseases sympatric with the Wisconsin populations, and which seemed to keep the popula- Saratoga spittlebug, and any of these pests concurrently tions under some control. Other identifiable factors could con- operating in a stand could compound the situation. The spit- tribute to population decline, but none that were observed tlebug affects small and large saplings (fig. 33) and so do many seemed able to do so. other pests.

The adult spittlebug is a parasite itself in the way it directly af- The alternate hosts, too, have their natural enemies. Sweetfern fects the tree through its feeding injury. Additionally, the adult particularly supports a veritable zoo of defoliators and sapsuck- poses an even greater threat to the tree through the possibility of ing insects. A soft scale was found killing patches of sweetfern transmitting disease pathogens. Cercopids are well-known vec- in a pine plantation in Michigan. Unfortunately the scale did not tors of viruses (Severin 1950, Delong and Severin 1950), and kill enough sweetfern stems to curtail the spittlebug. Aphids and the burn blight fungus is a well-known associate of the Saratoga leafhoppers are common residents as well. I studied several spittlebug adult. This disease sometimes occurs in spittlebug- sweetfern defoliators in an attempt to find a biological control of infested stands, especially on jack pine where it has killed this host. The sweetfern moth, Acrobasis comptoniella Hülst, is shoots, branches, and whole trees. Gruenhagen and others one of the more common ones, and it occasionally defoliates (1947) suggested that spittlebug is the vector and by weakening small patches of the host but probably has little effect because

Table 6—/./fe table of mortality for five generations of ttie Saratoga spittlebug on red pine in three Michigan plantations

Number alive at Range of Age beginning of Mortality Number Percent percent interval interval (per acre) factor dying mortality mortality

Egg 39,768 Nonviability 325 0.83 0.17-8.27 Parasitism 777 1.95 .16-12.78 Prédation 24 .01 0-.35 Incomplete development 734 1.86 .17-9.27 Incomplete emergence 1,600 4.03 1.44-11.39 Other 8,688 21.86 10.87-47.91 Total 12,148 30.54 23.64-60.49

Nymph 1-2 27,620 Desiccation Variable Prédation — — Moderate Other — — Variable Total 13,024 47.15 8.34-62.82

Nymph 3-5 14,596 Prédation Small Disease — — Variable Total 633 4.34 3.10-34.75

Adult! 13,963 Parasitism (Diptera) 1,030 7.37 1.64-11.95 Other 3,474 2.49 22.90-93.28 Total 4,504 10.86 4.23-94.00

Generation mortality: 64.89% (range: 43.48-98.83) Sex ratio (female:male): 1.00:0.97

^Adult samples taken before all eggs deposited; mortality would have been higher later in the season from prédation and other factors.

34 sweetfern tends to resprout rapidly. Besides, Acrobasis has at percent by the pipunculid (probably Verrallia virginica) reduced least 16 known parasites that keep its populations in check spittlebug population in Wisconsin (Ewan 1961). (Wilson 1970). Biological control of sweetfem by either defoliators or sapsuck- Other sweetfem defoliators include the leaf tier, Aroga argutiola ing insects so far shows little promise. Hodges; the sweetfem underwing, Catocala antinympha (Hübner); and the moth Nemoria rubrifrontaria Packard (Wilson Chemical control—The spittlebug became a pest problem con- 1974, 1975, Wilson and Heaton 1974). None of these are ever currently with the development of DDT; consequently, it was numerous enough to be a threat to sweetfem. one of the first forest insects to be tested and controlled with DDT. In 1943, a year before DDT was tested, Secrest (1944) Prevention and Control Tactics said that the use of chemicals would be unsatisfactory because the adults were sucking insects and a contact insecticide would Numerous researchers have attempted various tactics to prevent be needed. He tried pyrethrin and found that although it would and control spittlebug outbreaks by using cultural, chemical, and kill spittlebugs in cages, it was useless in the field because the other means against the insect or its alternate hosts. Techniques slightest disturbance sent the adults flying away. The arsenicals that have been proposed or tried are presented here. A few have in vogue during the 1930's were stomach poisons and useless on proven useless, others are outmoded, and some are of historical the spittlebug. Fortuitously, DDT was the "right" insecticide value only. Certain approaches, however, show promise for the and was used from 1945 to about 1963. It was used in a quan- present and for future spittlebug management programs. tity that qualifies the spittlebug as the most chemically treated forest pest on National Forest System lands in the Northeastern Prevenf/on—Secrest (1944) was the first to suggest that the United States (Fowler and others 1986). quantity of alternate host material was important for spittlebug buildup and proposed that trees should not be planted where Working in Wisconsin in 1944, Anderson (1945b) applied five sweetfem was abundant. Years later, Wilson and others (1977) pesticide formulations, one of which was DDT, to caged spit- showed the relative value of sweetfem and other alternate hosts tlebugs on jack pine trees. The cage tests showed relative dif- for spittlebug population buildup. Considering that new planta- ferences in pesticide toxicity (table 7); the field tests gave tions have small trees and the alternate hosts grow and spread similar results at first, but only DDT held up over time. After 8 somewhat in the years following planting, fields proposed for weeks in the field tests, 89 percent of trees treated with DDT planting should have no more than the following paired percent- still showed no spittlebugs. Secrest (1946), who made the first ages of sweetfem and other hosts: 0/40, 10/30, 20/10, and 25/5. aerial spray tests with DDT, used dosages of 0.25, 0.5, 1, and Higher percentages could support spittlebug populations that 2 lb/acre in 1 gal of kerosene or fuel oil. The best control was a might injure the trees. At the above paired percentages, spit- per acre dosage of 2 lb of DDT in 1 gal of oil. Other dosages tlebugs seem not to be able to damage a tree more than lightly. were unsatisfactory, except 5 lb in 3 gal of oil. This gave ex- However, if all the sweetfem is in large clumps, pockets of cellent control but was thought excessive. More DDT tests were trees may be injured. made by Milliron (1949), who found DDT at 1 and 2 lb/acre gave 98 and 100 percent control after 72 hours. Both dosages Cultural and biological confro/—Cultural methods and seemed satisfactory, but the oil carrier at the 2-lb dosage acted biological agents have great potential for reducing spittlebug as a herbicide by spotting Rubus plants and causing some leaf populations but methods are still unknown. Plowing under and fall. Because the 2-lb dosage inadequately controlled Rubus, he mowing sweetfem were attempted, but in most cases the recommended the 1-lb dosage for future spray programs. treatments only stimulated growth of the plants. Site is important for pine and for sweetfem, which seems to do best on the sandier sites marginal for pine. Table 7—Toxicity of several cliemical insecticides to Saratoga spittlebug adults in cages on treated pine branches'* Closely spaced trees, when growing well, shade out sweetfem. Cone, of Mortality Secrest (1944) suggested planting pines with some hardwoods to Insecticide give shade because he noticed that spittlebugs were worse in (0/0) 24 hr 48 hr open stands. He felt such mixed stands would have better site quality because of the hardwoods, and the hardwoods would DDT 1.0 96 100 help shade out the sweetfem. This would also encourage certain Sabadilla + wildlife. hydrated lime 20-80 97 100 Hydrated lime 100 62 91 Bordeaux 4.8 14 32 Researchers have not yet attempted increasing or augmenting Lime-sulfur 2.4 9 22 parasites, predators, and diseases. Egg and adult parasites seem iData taken from Roger F. Anderson. DDT and other insecticides to control the to be best prospects for control. Adult parasitism in excess of 60 Saratoga spittle insect on jack pine, 1945.

35 As DDT was phased out because of its various undesirable ef- 1969 (Wilson and Kennedy 1968, 1971). Granular propoxur, fects, scientists tried to find safer chemicals at lower dosages. aldicarb, carbofiiran, and phorate greatly reduced the nymphs at Mist-blower tests with 0.5- and 1-lb/gal/acre dosages of 0.5 to 3 lb/acre rates, and the suppression was comparable to malathion were tried, and both dosages controlled more than 99 malathion (tables 8 and 9). Liquid propoxur and carbofuran con- percent of the spittlebugs (Millers and Wilson 1965). The only trolled only at the 2- and 3-lb/acre rates. The other chemicals problem with malathion was that its effectiveness lasted only tested—dimethoate, disulfoton, fenitrothion, and oxydemeton- about 2 days in the field. Large-scale tests using helicopters methyl—were not effective at the formulations and dosages tried. followed. These tests proved that malathion by air at 1 Systemics have not been used in large-scale control programs Ib/gal/acre was better than 0.5 lb/gal (Wilson and Millers 1966). but should be considered in the future because they can be used A low-volume malathion formulation applied at 10 oz/acre was 1 to 2 months before adults emerge. Timing is usually planned equally good. The latter's major advantage, besides reducing the for early to mid-June to get the third or fourth instars during dosage by one-third, was that its bulk was one-twelfth that of migration onto sweetfern. Sweetfern requires a week or more to the normal oil-based dosages, so that aircraft could cover many translocate the chemical. more acres with each load. Large-scale programs in 1969 using malathion (Cythion LV 95 percent) controlled 98 percent of the The advent of new and promising pesticides prompted further spittlebugs and proved the value of using low-volume dosages tests against the adult spittlebug. Satisfactory control resulted in and a safe chemical such as malathion. registration of carbaryl and chloropyrifos.

Though malathion was satisfactory, its short residual retention Table 9—Toxicity of mist-blower applications of various systemic made timing critical. In large control programs, it became insecticides on Saratoga spittlebug nymphs feeding on sweetfern^ difficult to spray precisely after complete adult emergence and Application rate Percent before too many eggs were laid. This prompted the testing of Insecticide systemic chemicals against the nymphs on their alternate hosts. (lb/acre) mortality One early test against the nymphs was tried using DDT at 0.5, 1, and 2 Ib/gal/acre. The chemical was applied over jack pine Propoxur (cone.) 3 100 2 100 plantations prior to nymphal eclosión in order to kill the young 1 92 nymphs, but control was poor and most nymphs survived (Bess 0.5 29 and Eaton 1948). Propoxur (diluted 1:5)2 3 99 2 98 The systemic chemical propoxur was tested as a granular for- 1 86 mulation to control nymphs in 1966 and 1967 at 0.5, 1, 2, and 0.5 28 3 lb/acre. Control ranged from 97 to 100 percent, suggesting that systemics were effective in combating the spittlebug in the Carbofuran (wp) 3 100 nymphal stages. This success led to further tests in 1968 and 2 100 1 66 .05 41 Table S—Toxicity of granular systemic insecticides on Saratoga spittlebug nymphs feeding on sweetfern^ Carbofuran flowable (diluted 1:5) 2 95 1 76 Application rate Percent 0.5 66 Insecticide (lb/acre) mortality Dimethoate (cone.) 49

Propoxur (5%) 3 100 (diluted 1:5) 2 0 Disulfoton (10%) 3 48 1 0 Aldicarb (10%) 3 100 0.5 0 2 100 1 98 (wp) 2 0 0.5 98 Disulfoton (cone.) 3 0 Carbofuran (5%) 3 100 2 100 (diluted 1:5) 3 0 1 100 0.5 98 Fenitrothion (diluted 1:5) 2 0 1 0 Phorate (10%) 3 99 0.5 0 2 96 1 92 Oxydemeton-methyl (cone.) 0.5 94 iData taken from Louis F. Wilson and Patrick C. Kennedy, Control of Saratoga spit- iData taken from Louis F. Wilson and Patrick C. Kennedy, Control of Saratoga spittlebug nymphs with systemic insecticides, 1971. tlebug nymphs with systemic insecticides, 1971. 2Dilutions—chemicahwater.

36 Herbicida! coníro/—Herbicides have also been tried for con- but because it was phytotoxic to jack pine, expensive, and did trolling the nymphal hosts. Researchers tested 2,4-D on not kill blueberry, it was rejected in favor of glyphosate. sweetfern in the 1950's and 1960's with generally poor results Glyphosate at 2 and 3 qt/acre controlled the best, even 3 years (North Central Forest Experiment Station file report). Linnane after treatment (table 10). Heyd and others (in press) recom- and Osgood (1976b) tried one to three applications of 2,4-D to mended that 2 qt/acre be applied in the late summer because it kill sweetfern and lambkill. The herbicide killed the tops of the reduced sweetfern 83 to 100 percent. After 3 years, sweetfern plants, but nymphs developed on the stems without apparent recovery was only 4 percent and part of that was from invasion harm. One season later, however, 90 to 95 percent of the plants and edge effect of the plot tests. Recall that spittiebug popula- were gone and the nymphal population was down. Apparently, tions seldom reach destructive levels until 25 to 30 percent of timing for application was not critical and Linnane and Osgood the ground is covered by sweetfern (Kennedy and Wilson 1971). (1976b) recommended treatments from mid-June through July. Hexazinone applied in April or May at 1.5 to 2.0 lb active Heyd and others (in press) controlled sweetfern with fosamine material/acre has shown some promise in northern Wisconsin. It ammonium and glyphosate in late summer. Fosamine ammonium controlled sweetfern for at least 2 years and probably longer. applied at 1-, 2-, and 3-gal/acre dosages killed the sweetfern,

Table 10—Recov^eAy of sweetfern following herbicidal treatments^

Herbicide Mean percent sweetfern Herbicide applied/ acre Pre-treatment 1st yr 2nd yr 3rd yr

Fosamine ammonium 3 gal 36 1 2 gal 32 5 1 gal 31 5 Glyphosate 3 qt 37 6 2qt 31 4 1 qt 42 10 iData taken from Robert L. Heyd et al., Managing Saratoga spittiebug Aphrophora saratogensis (Fitch) in pine plantations by suppressing sweet-fern. Northern Journal of Applied Forestry [In press] '

37 Surveillance

Survey Methods PROPOSED PLANTING SITE

Young pine plantations need to be monitored for the Saratoga PLANTATION spittlebug until they are beyond risk of injury. Several kinds of surveys are available to forest managers for rating the risk of potential damage and for detecting, evaluating, and suppressing spittlebug populations (Benjamin and Beckwith 1956). Risk of injury, however, begins before the trees are planted because the composition of the alternate hosts on prepared planting sites af- LOW RISK HIGH RISK fects spittlebug survival. Several steps are involved in assessing -^7 the influence of the Saratoga spittlebug on the management of proposed pine planting sites or established plantations (fig. 35). Briefly, when there is a threat of spittlebug injury, a proposed ' MEDIUM RISK planting site or young pine plantation not yet injured should first NO /-^ be rated for potential injury by using the alternate hosts as an RESTRICTIONS /^ index of risk. If such rating indicates low risk, no further action \ is needed. Moderate or high risk ratings entail a balancing of the cost benefits of various management alternatives before pro- 1 EVAL UATE \ ceeding. The alternatives then are 1 COÍ 5T- . .\ BFNF FITS A • not to plant trees on a new site or, in plantations beyond ^(+) DO NOT PLANT PLANT AND/OR recovery, to bypass treatment prescriptions; PLANTATION REDUCE • to plant trees on a new site, and/or reduce alternate hosts in BEYOND RECOVERY {+) ALTERNATE HOSTS well-stocked plantations; or ♦ • to monitor the stand and, if appropriate, control the ACCEPT RISK spittlebug. Surveillance is involved in all the steps in this process. The various kinds of surveys follow.

Risk

Risk-rating—Prospective pine sites should be risk-rated for potential spittlebug injury before planting (Wilson 1971b, Wilson and Heyd 1978). Established plantations, too, can be risk-rated. Risk-rating should be conducted between May and July so that alternate hosts can be easily identified. The procedure, however, must be completed by mid-June in young plantations so control CONTROL measures can be applied if needed that year. Note that well- UNLIKELY stocked stands of pine taller than 5 m and not yet showing visible spittlebug injury symptoms are safe and need not be risk- rated. Trees over 6 m tall are usually safe at any stocking density. Brood-trees with spittlebugs and adjacent spittlebug-infested stands increase the the probability of spittlebug injury and should be considered when risk-rating a prospective planting site.

There are three risk categories—low, moderate, and high. Low risk means that injury from spitflebugs will not occur or, at most, will be negligible. Moderate risk indicates that spittlebugs Figure 35—Decision-making guidelines and probable conse- could cause some growth loss, light flagging on scattered shoots, quences of Saratoga spittlebug management. (See Management and crooked stems on a few trees. High risk indicates that spit- Guidelines section for details.) tlebugs will cause heavy growth loss, many crooked stems, and numerous top-killed or dead trees. when determining the risk of injury to young pine stands. Saratoga spittlebugs cause economic damage only when suitable Because sweetfem is the most important alternate host, risk- alternate hosts are abundant. Thus, one must consider the kinds rating is done by estimating and comparing the relative amounts and density of alternate hosts when selecting planting sites or of sweetfem and other suitable nymphal hosts (fig. 36).

38 coordinates intercept on the graph indicates the risk class for the area rated. For example, if you plot 10 percent sweetfern against 20 percent other hosts, the risk given by the graph is low. If, however, you plot 30 percent sweetfern against 30 percent other hosts, the risk is high. Place an L, M, or H at each stop to indicate low, moderate, or high risk, respectively. While walking transects, observe and note any changes in overall ground cover so that you can draw boundaries between areas of different risk. This is especially important for sweetfern, which has a tendency to form large clumps. If you have difficulty distinguishing a risk category (e.g., moderate from high), favor the greater risk.

4. After completing all observations, draw lines on the sketch or map that enclose areas of similar risk (fig. 37).

5. Estimate the acreage in each risk category. 10 20 30 40 50 60 70 80 PERCENT SWEETEERN 6. See Management Guidelines (page 44) to formulate a plan of action. Figure 36—Saraioga spittlebug risk categories based on percent sweetfern compared to percent otiier alternate hosts. Aerial fî/sIc-Rai/ng—Risk-rating prospective plantings and plantations is particularly easy and cost effective with a helicopter when many acres need assessing or time is especially Risk-rating presupposes that a proposed site or plantation has or short. A person experienced with the ground risk-rafing pro- will have at least 600 trees/acre. Fewer trees increase the risk. cedure can do an aerial survey over the same area in minutes.

Risk-rate unplanted land between May and July for best results. Risk-rate plantations in May or early June in order to follow up with nymphal surveys. You will need the following equipment: sketch map of the area, instructions and risk-rating form (page 53), clipboard, and pencil. To risk-rate an area proposed for H H / M M planting pine or an established pine plantation:

1. Draw transect lines on planting sketch or map. Make H H y M j transects parallel and spaced 2 to 5 chains apart (1 chain = r^ 66 ft or 20 m). Use 5-chain spacing on unplanted land with H /M M/ L good visibility; use a spacing as close as 2 chains where the lateral view is inhibited by trees and/or terrain. H y M > ^L L 2. Walk transects. Stop every 1 to 2 chains to observe the ground cover. First, estimate percent of ground cover occupied by the sweetfern canopy and then the percent oc- M L L cupied by nonhosts (i.e., grasses, sedges, lichens, mosses) r^ and bare ground. Then estimate percent of the other host M L L plants (all other broadleaf herbs, ferns, small trees, etc.) or '^^ calculate this percent by subtracting the percent sweetfern and percent nonhosts from 100 percent. M M M ^ 3. Use risk-rating triangle to determine if risk is low, moderate, or high at each stop. Plot the percentage of V sweetfern against the percentage of other hosts on the Figure 37—Sample risk-rating map delineating areas of similar triangular graph on the form (fig. 36). The point where the risk.

39 Low-risk areas are readily distinguishable from moderate- and To make a Saratoga spittlebug detection survey from the ground, high-risk areas, and the observer gains an excellent perspective you will need a knife, vials, and an insect sweep net—a collect- of the amount and distribution of different risk zones. Aerial ing net with a muslin bag instead of the typical net bag. To take risk-rating is also an excellent way to screen sites rapidly and a detection survey: determine whether ground checks are needed. To risk-rate by 1. Detect damage. Look for gross symptoms of spittlebug damage such as flagging (reddish shoot tips), topkill, or 1. Assign areas to low-, moderate-, or high-risk categories. dead trees. These are present only in moderate to heavy in- You may have to rely mostly on the amount of sweetfern as festations (cover photo). Table 11 gives the various gross the principal component of the ground cover. The risk is symptoms from spittlebug feeding and their ease of low when sweetfern makes up less than 15 percent, detection. moderate when it makes up 15 to 25 percent, and high when it makes up more than 25 percent of the vegetation. 2. Detect injury. Examine 1-year-old shoots for feeding wounds and scars (any time of year). You will need to 2. Draw boundaries of the categories on the sketch map pro- scrape off the bark of the shoot with a knife or other sharp vided on the Risk-rating Survey Field Form. blade to see these injuries (cover photo).

3. Determine the acreage in each category. 3. Detect eggs. Search for eggs (August through the following April only). Examine the leader or top whorl buds. 4. Refer to the Management Guidelines (page 44) to formulate You can feel or see the eggs as bumps on the surface or a plan of action. see them protruding from the bud scales (fig. 14).

Detection 4. Detect nymphs. Search for spittlemasses and nymphs (mid-May through early July only). The nymphs will be in- Detection survey—The purpose of a detection survey is to side the spittlemasses at the bases of sweetfern and other learn whether the Saratoga spittlebug or its damage is present at ground cover plants (back cover photo). any particular time or place. It can be made casually or systematically, whichever the observer desires. It is usually a 5. Detect adults. Search for adults (mid-July through August ground survey, but it can be made from the air when the in- only). Use an insect sweep net and sample one or several festation is sufficiently heavy to show gross symptoms such as trees for adults. Run the net up the foliage, and, at the end nagging, topkill, or dead trees (table 11). Ground checks, of the swing, flip the end of the net over the ring to close however, may also be needed to verify the insect's presence, the bag. You may need to catch the adults in a bottle or because a few other insects and some diseases such as scleroder- vial to identify them because they may fly away when the ris canker cause similar gross symptoms of damage. bag is opened.

Table 11 —Progression, ease of detection, and feeding intensity needed to produce gross symptoms of spittlebug damage to red pine

Feeding intensity Damage symptoms Ease of detection Seasons needed preceding symptoms Slight uneven reduction in Detected only by careful Summer 2 or more years of light to lateral shoot elongation lateral-terminal growth moderate feeding measurements

Barely perceptible yellowing Difficult to detect even with Fall-winter 1 or 2 years of moderate to of foliage on 2-year-old normal foliage for heavy feeding growth of lateral branches comparison

Dead shoots Easily detected, mostly on Spring-summer 2 or 3 years of heavy feeding Foliage yellow to red upper part of tree (flagging) Stunting

Dead branches, tops, and Easily detected, generally oc- Spring-summer 3 or more years of heavy trees curs in clusters, with abun- feeding Crooked and misshaped trees dant alternate hosts

40 You may stop the survey after step 2, 3, 4, or 5 if the feeding 8. Average the number of scar counts from the samples. If the injury or the insect is collected and verified. Note that when in- average is less than 25, the stand is still safe (with a festations are too light to show injury, you may need to sample chance of 9 of 10 times), and a nymphal survey is not re- several trees or alternate hosts before locating the spittlebug. quired the next season. If the average scar count is between 20 and 25, the area should be scar-surveyed again Aerial detection survey—When damage is pronounced, detec- the next year. If the average scar count is greater than 25, tion also can be made by helicopter or from small-scale aerial the stand should be surveyed for nymphs in the spring color photographs. Ground checks should be made, nevertheless, (Nymphal Appraisal Survey, below). to verify the insect. Infrared photographic detection prior to visible injury has been tried but found wanting (Latham and Millers Nymplial appraisai survey—A survey of spittlebug nymphs 1970). determines the current threat of injury. Damage in terms of growth loss, deformity, and tree mortality is estimated from the Evaluation number of spittlebug nymphs relative to the number and size of trees in a stand. Begin looking for nymphs in spittlemasses the Feeding scar appraisai survey—This survey estimates the second week of June and not later than the third week. Tally the severity of adult feeding, which in turn predicts whether a more nymphs when most are late instars (third to fifth instars). detailed nymphal survey should be made the next season. The Younger nymphs are difficult to find and late instars more ac- survey is usually made in fall, after spittlebug feeding, but it can curately reflect the adult population that injures the trees. The be made in winter or early spring. This is a good way to first four nymphal instars are black and red; fifth instars are monitor the population without investing a lot of time and effort. chestnut brown. When you find a few of the brown nymphs, it For this survey you will need a sketch map of the area, a knife, is time to survey. a pencil, and a clipboard. Also, because this is a sticky job, you may wish to carry some rubbing alcohol and a cloth to clean If the current threat does not warrant concern, nothing further your knife and hands. To make a feeding scar survey: needs to be done that year. However, nymphal surveys should then be scheduled periodically until the trees are 15 ft (5 m) tall 1. Sample only areas with moderate or high risk. (See risk- or their crowns close, whichever comes first. rating survey, page 53.) For a nymphal survey you will need a sketch map of the plant- 2. Determine the number of samples you will take according ing with risk areas delineated (from Risk-Radng Field Form, to the following acres at risk: page 53), clipboard and pencil, four flags or stakes, a measuring Acres Samples needed pole (in feet), a square sampling frame 25 in by 25 in (inside <11 20 measure), and the insect evaluation instructions and the Nymphal 11-20 25 Survey Form (page 55). To take a nymphal appraisal survey: 21-50 30 >50 35 or more 1. First survey the areas of high risk on the risk-rating map. If some areas qualify for control, then survey moderate- 3. Conduct the survey systematically by walking and sampling risk areas also. at some reasonable interval such as every chain (66 ft or 20 m), tenth row, etc. Plot sample points on a map of the 2. Select the number of 1/10-acre sample plots needed area ahead of time. The idea is to get good coverage of depending on plantation size. moderate- and high-risk areas and to do it economically. No. of plots Acres in high risk 1 1-5 4. Select an average tree at each sample point. 2 6-10 3 11-20 5. Select a branch from the upper half of the tree and cut a 4 21-40 4-inch section from the center of the 2-year-old growth (the 5 40 + penultimate internode). 3. Establish 1/10-acre sample plot (66 by 66 fl), demarcating 6. Scrape off the bark of the 4-inch sample with a knife and the four corners with flags or posts. Pace off the plot or count and record the number of scars (red flecks) on the use a 66-ft tape or rope. wood (front cover). Mark each scar with an indelible pencil or felt pen to prevent missing or recounting scars. 4. Count the number of trees in the sample plot.

7. Repeat sampling until all counts have been made and 5. Determine the average number of whorls per tree. If the recorded. trees are the same age, you can determine this easily from five trees.

41 6. Measure height (to nearest half foot) of 10 trees scattered Table 13—Key to action recommended after nymphal appraisal throughout the plot. Then determine their average height. survey'^ Oa. Nymphs/tree-unit less than 1.0—see no. 1 7. Calculate and record the tree-units for the plot by multiply- Ob. Nymphs/tree-unit 1.0 or more—see no. 8 ing the number of trees by the average number of whorls by the average tree height. 1a. Trees shorter than 10 ft—see no. 2 1b. Trees 10 ft or taller—see no. 4

8. Count the number of nymphs in 50 one-tenth milacre 2a. Nymphs/tree-unit less than 0.15—evaluate again in 3 years samples using the 25-in by 25-in sampling frame. Begin at 2b. Nymphs/tree-unit 0.15 or more—see no. 3 one corner of the plot and proceed systematically along the rows of trees. Take samples about 5 or 6 ft apart to get 50 3a. Nymphs/tree-unit more than 0.25—evaluate next year 3b. Nymphs/tree-unit 0.15 to 0.25—evaluate in 2 years samples evenly spaced throughout the plot. Regularly stagger the sampling locations so that some are taken in the 4a. Trees from 10 to 12 ft—see no. 5 lane between rows and others are taken close to the trees. 4b. Trees taller than 12 ft—see no. 7

5a. Nymphs/tree-unit more than 0.15—see no. 6 9. At each sample location, drop the frame, being sure not to 5b. Nymphs/tree-unit 0.15 or less—no need to reevaluate preselect or omit specific plants as you locate the sample. Carefully examine all host plants for nymphs, which will 6a. Nymphs/tree-unit more than 0.25—evaluate next year be in spittlemasses at their bases. When you find one live 6b. Nymphs/tree-unit 0.15 to 0.25—evaluate in 2 years nymph, stop sampling and record the sample as a plus (+). 7a. Nymphs/tree-unit more than 0.40—reevaluate next year If no nymphs are found after examining all host plants, 7b. Nymphs/tree-unit 0.40 or less—no need to reevaluate record the sample as a negative (—). Move to next sample and repeat. 8a. Nymphs/tree-unit 1.0 to 2.0—if there is flagging or noticeable degradation, control this year; if not, reevaluate next year 10. Afler taking 50 samples, count the pluses (-\-) and multiply 8b. Nymphs/tree-unit more than 2.0—control this year

by 2 to determine the percent samples infested with ■"Given near threshold values, use indicators of the previous year's feeding injury to help nymphs. The percent samples infested provides an estimate nnake a control decision. The previous year's feeding scars persist to add to the present year's injury; thus, use presence of feeding scars, flagging, and the previous in- of the number of nymphs for the 1/10-acre plot. Calculate sect evaluation, if available, to decide if control is warranted. and record the nymphs per tree-unit by taking the number of nymphs per plot and dividing by the number of tree- units per plot. The nymphs per tree-unit gives the potential damage level. (See tables 12 and 13.) Suppression

Predicting control date—Adult spray programs are usually timed so that the chemical is applied when about 80 percent of the adults have emerged. Though this occurs in July, Table 12—Damage level categories for adult spittlebug feeding temperatures are sufficiently variable to make the control date . . K. u IX x Potential growth vary over a 2-week period from year to year. Timing is Damage level Nymphs/tree unit reduction (o/o) especially critical with chemicals that have short residual lives. Very /ow—lateral terminal Spray programs usually begin in southernmost areas and proceed growth differences 0.25 2 northwards because emergence usually varies a few days from south to north. Predicting control dates from nymphal develop- Low—up to 4 yr of growth ment is not reliable, so the standard way of predicting the date reduction 0.50 6 is by actually observing adult transformation. You will need one /Woderafe—up to 10 yr of or several open-ended rearing cages for this exercise. (A growth reduction, scattered description of a simple, inexpensive cage follows on page 43. ) flagging, some degradation 1.00 25 To predict the control date: H/g/7—whole-branch flagging, dead tops, extensive 1. In late June select a large sweetfem plant in the open that degradation, some dead has one or more spittlemasses with numerous nymphs. trees 2.00 41 2. Count the nymphs in the spittlemass(es). You'll want about Very high—óeaó tops, extensive degradation, many 40 insects, so either add nymphs to the spittlemass from dead trees 6.00 66 others nearby, or plan to set up enough cages to total 40 or more nymphs.

42 3. Set up the cage (instructions follow) over the sweetfern plant.

4. Each morning examine the cage for adult spittlebugs—Û\e,y usually sit on the walls of the cage. Remove the adults and keep a running tally of the number that have emerged. 5. Remove adults daily until half the nymphs have emerged.

6. Begin control spraying about 3 days later. If temperatures have been especially warm, 2 days later is the best predicted date; if especially cool, 4 days later is the best date.

A simple cage, useful for determining when spittlebugs transform, is easy to build, collapsible, readily portable, com- pact, and inexpensive (Wilson 1971a) (fig. 38). The cage is made of plastic window screen and the dimensions are 36 in high (cage opened on top) by 16 in on a side. The walls are supported by four pointed wooden stakes 0.5 in square by 28 in long that protrude 4 in beyond the bottom edges of the cage. Ordinary staples from a staple-gun hold the netting on the stakes. The comer seam of the netting is sewn by hand or Figure 3B—Rearing cage for adult Saratoga spittlebugs shown machine with plastic thread. The cage can be built to various both in position over a sweetfern plant and rolled up for transport dimensions. and storage.

In use, the stakes are driven into the ground around the plant 2. Select trees to be sampled and sweep each tree once with and the top is folded in and over to resemble the top of a paper the sweep net, quickly moving the net upwards along the milk carton (fig. 38). Four medium binder clips secure the top. tree's foliage from the lowest branch to as high as you can Lx)ose soil is packed around the base of the cage on the edge of reach. the netting to make the cage escape proof. When not in use, the cage lies flat and can be rolled up tightly to store or transport 3. Count and record adults captured after each sweep. If the (fig. 38). population is low, you may be able to make several sweeps before counting. Pre- and post-control appraisal survey—The efficacy of a chemical control treatment can be assessed by counting popula- 4. Empty the net and repeat sampling along the transects until tions of adult spittlebugs 1 to 2 days before and 1 to 2 days all samples are taken. after treatment. The survey is most reliable if the counts are taken by the same observer at about the same time of day. The The effectiveness of the treatment can then be determined by in- survey requires only a sturdy insect sweep net, pencil, and serting the sweep counts in the following formula: notebook. To take one of these surveys: percent control = 1. Set up transects in the plantation and plan to take at least No. of bugs pre-sweep - No. of bugs post-sweep 100 sweep-net samples throughout. X 100. No. of bugs pre-sweep

43 Management

Management Guidelines certain circumstances it can have a positive effect on the forest ecosystem. A spittlebug outbreak used wisely can help land The Saratoga spittlebug can be managed by preventive, cultural, management in a manner similar to the use of prescribed burn- and chemical measures. It can also be managed by doing ing. This does not mean that an outbreak should purposely be nothing—that is, by letting an infestation run its course. initiated but rather that an existing outbreak can be allowed to run its course when its effects are deemed advantageous to Prevention involves restricting the planting of spittlebug- forest management. What is suggested is a change in thinking, susceptible pines to only no-risk or low-risk areas. This may from "all insects are bad and must be suppressed vigorously" to mean not planting an entire area or omitting just a few small "let's evaluate the situation and capitalize on it if possible." islands or pockets where the important alternate hosts pre- dominate. Not planting a small portion of an area may greatly In practice, spittlebug management is basically a concern of enhance esthetic and/or wildlife values in some regions. Pockets economists because it involves social and economic considera- with 35 percent or more of the ground cover in sweetfern are tions. It is the economists' job to describe the effects of the in- especially troublesome, and if planted and then infested, there is sect in socioeconomic terms useful as decision-making criteria a nearly certain probability of high injury without control. Even for land managers. Such an economic analysis can be found in if not injured greatly by spittlebugs, trees in such areas usually the section Selecting a Management Strategy. Here, however it grow slowly until their crowns close because of direct competi- is useful to point out how some of the effects of the spittlebug tion from sweetfern. might relate positively or negatively to land management goals under a multiple-use concept. Cultural control mainly involves reducing the principal alternate hosts—especially sweetfern. Deep plowing disrupts and buries Timber—Pines are managed primarily for wood products, so sweetfern and usually curtails rapid regeneration. However, deep the spittlebug is essentially an economic pest. Spittlebugs kill plowing can disrupt soil structure and water-holding capacity of and deform young pines growing in high stress areas where the plowed soil layer, which may cause a critical situation in there is abundant sweetfern. These areas often have indices for sandy soils. Shallow plowing or mowing stimulates sweetfern red pine near or below 50. The better (without sweetfern) areas growth and should be avoided unless repeated for 2 to 3 years, may have site indices 60 or higher. Manthy and others (1964) which may be prohibitively costly. Chemical herbicides seldom showed that well-stocked red pine stands of site index 60 will disturb the soil and provide what appears to be the most return financial yields for pulpwood rotations from about 2 to 5 reasonable method of reducing ground vegetation. Herbicides percent and for sawlog rotations from 3 to 7 percent. In con- suppress sweetfern, brambles, and certain other alternate hosts trast, the trees with a site index of 50 can expect a financial when applied properly and seem to provide long-term suppres- yield of less than 3 percent for pulpwood rotations and from 3 sion, which will benefit future crops. to 5 percent for sawlog rotations, and then only if appropriate stocking is maintained. Sometimes less than one-third of the Pesticides kill nymphs and adults, but control is usually directed original trees remain in sweetfern pockets after an outbreak, and against the adults. This means that pesticides must be applied surviving trees are deformed and unevenly dispersed over the precisely between adult emergence and egg laying (usually early area. Merchantable volume then would yield less than 1 percent July). In high-risk areas, two or three applications may be on these sites and would certainly not be worthy of additional needed before the trees outgrow the risk. The nymphal evalua- forest management input as far as forest products are concerned. tion survey provides the most accurate predictor of adult popula- In areas where the spittlebug does less injury, an economic tion and injury and is recommended for making management analysis should be conducted to help decide management decisions. practices.

Socioeconomic Considerations From the current viewpoint of the land manager, the spittlebug has a negative effect on the financial yield of pine. Large low- Land managers are concerned with satisfying human needs quality sites or extensive sweetfern pockets sometimes might bet- relative to available natural resources; their goals are to supply ter be left unplanted in the first place and thus be available for wood, water, forage, wildlife, and recreational opportunities. other more productive uses. Sweetfern sites, of course, can be planted, but losses should be anticipated and planned for in the The Saratoga spittlebug, like most other forest pests, is usually overall management objective. thought of as a deterrent to the achievement of one or more of these management goals because it appears to cause a negative Wildlife—Most plantations, especially red pine plantations, pro- effect on the forest and associated land. Consequently, spit- vide little variety and hence are generally unfavorable as a long- tlebugs have historically been evaluated in terms of adverse im- term habitat for edge wildlife species such as deer, bear, hare, pact rather than in terms of their effect on land-use goals. The and grouse. The early stages of a plantation briefly provide spittlebug need not always be perceived as destructive, for under some habitat for some edge wildlife.

44 Mature red pine stands are generally favorable for interior pears to have little or no long-term effect on water yield and wildlife species such as squirrels, owls, and warblers (Ohmann quality and only a slight short-term positive or negative effect and others 1978). Kirtland's warbler is an endangered species under conditions of extensive stand change. that requires young jack pine stands for nesting. Recreation and visual quality—Most pines become more Openings in large pine stands, if properly managed and kept esthetically pleasing as they age. The spittlebug seldom injures open for several years, can provide forbs, grasses, and shrubs trees more than 5 m tall. Young dying, dead, and deformed that supply food, nesting sites, and shelter for edge wildlife. trees are not esthetically pleasing. When someone encounters a Tubbs and Verme (1972) and Ohmann and others (1978) recom- spittlebug-injured stand, reaction varies from non-interest to ex- mended that wildlife openings be established in large stands, and citement or concern. Concern is often about the welfare of the McCaffery (1970) suggested that red pine not occupy more than trees, and the level of excitement depends on the degree of in- 30 percent of an area. The best places to create openings in a jury and on the ownership of the trees. Hunting opportunities stand or leave openings during planting are excessively or may improve from the change in edge wildlife habitat following poorly drained soils, on shallow soils, and in frost pockets a spittlebug outbreak. Fishing will probably not change unless (Tubbs and Verme 1972). These areas have little advance water quality changes due to silting or pesticide contamination. reproduction and are the easiest areas to maintain as openings. Tubbs and Verme (1972) also recommended that the openings Selecting a Management Strategy border trails and other timber types to provide a variety of vegetation and allow escape cover. Openings 1 to 10 acres in After risk-rating an unplanted area or pine plantation, decide size are best, and many smaller areas are preferred over a few whether ftirther evaluations are needed. If the risk is low, the large ones. Irregular shapes provide longer perimeters and thus potential damage is also low and ftirther evaluation is un- more edge vegetation and are esthetically more pleasing. necessary. If the risk is moderate or high, however, further evaluations, decisions, and actions are warranted (fig. 35). Large pockets of sweetfern fit the criteria suggested above for wildlife openings. As trees die on these sites, irregular openings Unplanted sites—On unplanted land that has been risk-rated appear that favor the edge wildlife species. Small clumps of re- as moderate or high, you have the option to plant and accept the maining pines provide ideal escape cover. Such sites can be risk, plant and monitor the insect and control a threatening managed to remain in the forb-grass-brush stage for many years. population, plant and reduce the alternate hosts for long-term And, if such areas are identified prior to planting, they can be control of the spittlebug, or not to plant. To select an left unplanted and managed exclusively for wildlife. economically sound strategy, a cost-benefit analysis should be made. That is, the costs of each strategy should be carefully The spittlebug then, can have a strong positive effect on weighed against the benefits, and then a strategy should be development of edge wildlife habitat. Many of the edge species selected that provides an acceptable return on investment. are also game species, so that proper management also enhances recreational opportunities. More specifically, the present value of returns (PVR) should be compared to the present value of costs (PVC) to derive the net Water yield and quality—Fines have relatively high present value (NPV) of a particular management strategy (NPV évapotranspiration and respiration losses, and thinning dense = PVR - PVC). This is done by discounting projected costs pine stands usually increases water yield (Urie 1971). Thus, and returns at the desired rate over the period in which each areas with trees killed by spittlebugs should have greater water cost or return is to be realized. If the resulting new present yield, but because these areas usually occupy only a few acres, value is greater than or equal to zero (PVR > PVC), the the increase would be small. Also, any changes would be for management strategy in question produces or exceeds the desired only a short duration because shrubs, grasses, and other vegeta- return on dollars invested. In addition, the size of the positive tion will eventually compensate for the pines and trap as much net present value indicates additional dollars that can be spent or more water. now, yet still achieve the given return. A negative net present value means the management strategy does not provide the Spittlebug-injured trees should not normally affect stream desired return on investment. Again, the size of the net present sedimentation and nutrient enrichment from waste products. value represents the dollar amount in present money (money that Because of the highly permeable soils characteristic of most pine can be spent now) with which a project either falls short of plantations, water quality could be affected if a pesticide were (-NPV) or exceeds (+NPV) the desired return on investment. used against the insect, and especially so if treated areas were adjacent to streams or lakes. The effect and duration of water An example of the costs and returns (on a per acre basis) of quality change would largely depend on the type and amount of managing a stand using a 60-year rotation with two thinnings is pesticide applied. At least in northern areas, the spittlebug ap- shown in table 14.

45 Table 14—Costs and returns of managing a hypothetical red pine 6.44 -\- (0.36 X no. cords harvested)). The upper and lower stand using a 60-year rotation with two thinnings limits of growth loss in a moderate-risk area are 4 and 10 years, respectively. Growth loss caused by the Saratoga spittlebug Year Operation Cost/acre Return/acre uniformly affects the productivity of the entire tree, so that height and diameter growth are reduced. Thus, reduced yields 1 Stand establishment $120 5 Spittlebug control 12 — from growth loss were calculated by using the volume yields of 10 Spittlebug control 12 — a rotation shortened by the years of lost growth. For example, 35 Thinning — $140 given 4 years' growth loss, the yield of this planting would be 45 Thinning — $400 calculated for age 41 instead of 45. 60 Final harvest — $1200 It is apparent (table 15) that accepting the risk of injury is not In the example in table 14, the an option for high-risk areas or for moderate-risk areas of site index 50 or less at the selected rates. The monitor and spray present value of costs = strategy consistently produces the highest return. Reducing alternate hosts is a much more expensive operation, yet it provides 120 + 112(1 +iy ^ 12 (1 + ¿y' greater NPV's in most instances than accepting the risk. The (1 + ry (1 + ry only exceptions shown in table 15 are for rates 8 to 9 percent in moderate risk (lower limit) on site index 70. However, any in- present value of returns = crease in productivity of the site from reducing ground cover competition was not considered because of a lack of yield data 140 (1 + ty^ _^ 400 (1 + ty^ _^ 1200 (i + ty^ for site indices greater than 70. The net present values for site (1 + r)35 (1 + r)45 (1 + r)6o indices 50 and 60 include an increase in yield reflecting a release from ground cover competition. This is shown most Where: dramatically in the high-risk areas with site indices of 50 and r = desired rate to be earned as a decimal (e.g., 0.07 for 7 60. Here, reducing alternate hosts yields higher NPV's than percent); monitoring and spraying. / = rate above inflation expected for costs or returns. For example, forest products may increase in value faster Reducing alternate hosts provides protection for future crops. than inflation. So, / for PVR may be set at 0.04 if a Thus, monitoring, surveying, and spraying may produce higher 4-percent increase above inflation is expected. returns for the present rotation; however, future plantings can still derive the benefits of reducing alternate hosts. net present value = present value of returns — present value of costs. P/anfaf/ons—Basically, the same procedure to make management decisions for proposed planting sites is used in established If there is a positive NPV, the management strategy pays at rate pine plantations. The present value of returns is calculated by r; the size of the value is money that can be spent now and still discounting the value of the crop at maturity by the number of earn rate r. years to maturity at the desired interest rate. The present value of returns (PVR) is then compared to the present value of costs If there is a negative NPV, the management strategy does not (PVC) for each management strategy (and any other costs to be pay at rate r. incurred) to calculate net present value (NPV). If the spittlebug deforms, kills, or slows the growth of the trees, the value of the An example of using net present value (NPV) to select the best crop at maturity is modified by the reduced yield caused by management strategy follows: these injuries.

Let's assume that we want to plant an area to red pine and that If monitoring and control is chosen as the best management this acreage has significant portions in the moderate- and high- strategy, a spittlebug nymphal appraisal survey should be risk categories for Saratoga spittlebug. We want to plant 600 scheduled. Injury in terms of growth loss, deformity, and dead trees per acre to be harvested at age 45. For the purpose of this trees is estimated from the number of spittlebug nymphs relative example, we set establishment cost at $116.72 per acre (Olson to the number and size of trees in a stand. (See Nymphal Ap- and others 1978). Any additional costs and returns expected will praisal Survey.) Control of the adult spittlebug is then recom- depend on the management strategy selected. mended on the basis of this survey.

Table 15 presents the net present values resulting from different If the current threat does not warrant concern, nothing further management strategies for site indices of 50, 60, and 70. The needs to be done that year. Surveys, however, should be yield in cords of each management strategy in the table is used scheduled periodically until the trees are taller than 15 feet to determine stumpage price (i.e., stumpage price per acre + (5 m) or their crowns close, whichever comes first.

46 Table 15—A/ef present values at four discount rate percents for different management strategies and site indexes on planting sites with moderate and high risk for Saratoga spittlebug (the proposed planting is 600 red pine per acre to be harvested at age 45)

Net present value ($/acre) at discount rate percent Moderate risk High risk Management strategy 70/0 8% 90/0 10% 7% 8% 90/0 10%

Site Index 70 Accept risk (lower limit)^ $246 122 41 -12 — — — — Accept risk (upper limit)2 216 83 3 -44 -117 -117 -117 -117 Reduce alternate hosts^ 265 114 15 -49 265 114 15 -49 Monitor and spraye 314 164 66 1 307 157 59 -5 No risks 325 174 75 11 325 174 75 11

Site Index 60 Accept risk (lower limit) 89 19 -27 -58 — — — — Accept risk (upper limit) 81 2 -45 -73 -117 -117 -117 -117 Reduce alternate hosts 132 27 -42 -88 178 57 -23 -74 Monitor and spray 136 46 -12 -50 128 39 -19 -57 No risk 146 56 -2 -41 146 56 -2 -41

Site Index 50 Accept risk (lower limit) -10 -47 -70 -86 — — — — Accept risk (upper limit) -6 -50 -77 -92 -117 -117 -117 -117 Reduce alternate hosts 1 -60 -100 -126 32 -39 -86 -117 Monitor and spray 14 -35 -67 -88 7 -42 -73 -93 No risk 31 -19 -52 -74 31 -19 -53 -74

1 Moderate risk (lower limit) = 4 years lost growth.

2Moderate risk (upper limit) = 10 years lost growth. However, yield at 45 years was discounted to age 55 because loss of 10 years growth at age 45 reduced yield below acceptable limits. High risk = total loss.

3Cost = $60/acre; reducing alternate hosts increased site index by 5 for moderate-risk areas and 10 for high-risk areas for site indexes 50 and 60. No data were available for yields on site indices greater than 70. sSpray cost—$12/acre for aerial application. Moderate risk areas were evaluated three times and sprayed once. High-risk areas were evaluated three times and sprayed twice. If site index is <50 add one evaluation and one spray to account for increased length of spittlebug-susceptible height stage (3 to 15 ft) due to slow growth. sYield expected with no threat of loss or need to control, presented for comparison.

Christmas trees—Scotch pine or Austrian pine Christmas trees port enough spittlebugs to cause some flagging. Red pine, if are vulnerable to Saratoga spittlebug injury when alternate hosts grown for Christmas trees, is very vulnerable to attack; eastern are abundant. Christmas tree stands should be kept free of white pine, however, is nearly resistant to injury even if mixed sweet fern and other primary alternate hosts as much as possible with other tree species. The cost of prevention and control in to prevent injury. Even clean-looking stands occasionally have Christmas tree plantings is economically justified when needed. abundant small forbs such as orange hawkweed, which can sup-

47 Literature Cited

Anderson, G. W. Sweet-fern rust on hard pines. For. Pest. Doering, Kathleen C. Synopsis of the family Cercopidae Leafl. 79. Washington, DC: U.S. Department of Agriculture, (Homoptera) in North America. Journal of the Kansas En- Forest Service; 1963. 4 p. tomological Society 3(3-4):53-64, 81-108; 1930.

Anderson, N. A.; French, D. W. Sweet-fern rust on jack pine. Doering, Kathleen C. Some biological notes on the Cercopidae Journal of Forestry 62:467-471; 1964. north of Mexico (Homoptera). Journal of the Kansas En- tomological Society 4(2):48-51; 1931. Anderson, Roger F. Biology of the Saratoga spittle insect. Washington, DC: U.S. Department of Agriculture, Bureau of Doering, Kathleen C. A revision of two genera of North Entomology and Plant Quarantine; 1945a. 21 p. American Cercopidae (Homoptera). Journal of the Kansas En- tomological Society 14(4): 109-134; 1941. Anderson, Roger F. DDT and other insecticides to control the Saratoga spittle insect on jack pine. Journal of Economic En- Doering, Kathleen C. Host plant records of Cercopidae in tomology 38(5):564-506; 1945b. North America, north of Mexico (Homoptera). Journal of the Kansas Entomological Society 15(2):65-72, (15)3:73-92; Anderson, Roger F. Saratoga spittlebug injury to pine. Journal 1942. of Economic Entomology 40(l):26-33; 1947a. Eaton, Charles B. The Saratoga spittlebug. For. Pest Leafl. 3. Anderson, Roger F. The Saratoga spittlebug. Journal of Washington, DC: U.S. Department of Agriculture, Forest Ser- Economic Entomology 40(5):695-701; 1947b. vice; 1955. 4 p.

Ball, E. D. Notes on the Cercopidae of America north of Mex- Ewan, Herbert G. The Saratoga spittlebug Aphrophora ico (Homoptera). Entomological News 39(2):4-49; 1928. saratogensis (Fitch), a study of gradients of feeding injury distribution on red pine, Pinus resinosa Ait., and notes on the Ball, E. D. The spittle insects of the genus Aphrophora occurr- diapausing egg. Spec. Rep. M-1. Milwaukee, WI: U.S. ing in the United States (Homoptera: Cercopidae). En- Department of Agriculture, Bureau of Entomology and Plant tomological News 45(7)175-179; 1934. Quarantine; 1953. 36 p.

Benjamin, Daniel M.; Beckwith, Leroy C. An evaluation of Ewan, H. G. Some effects of temperature extremes on Saratoga spittlebug population estimation techniques. In: Pro- Saratoga spittlebug populations. Tech. Note 519. St. Paul, ceedings, 11th annual meeting. North Central Branch, En- MN: U.S. Department of Agriculture, Forest Service, Lake tomological Society of America; 1956 March 28-30; States Forest Experiment Station; 1958a. 2 p. Lafayette, IN: Purdue University; 1956: 19-20. Ewan, Herbert G. The use of the host size and density factor Benjamin, Daniel M.; Batzer, Harold O.; Ewan, Herbert in appraising the damage potential of a plantation insect. In: G. The lateral-terminal elongation growth ratio of red pine as Proceedings, 10th International Congress of Entomology; 1956 an index of Saratoga spittlebug injury. Journal of Forestry August 17-25; Montreal. Ottawa: Mortimer, Ltd.; 1958b: 51(ll):822-823; 1953. 363-367.

Bess, Henry A.; Eaton, Charles B. Airplane spraying experi- Ewan, H. G. The Saratoga spittlebug: a destructive pest in red ment with Saratoga spittlebug, 1947. Rep. For. Insect Lab. pine plantations. Tech. Bull. 1250. Washington, DC: U.S. Milwaukee, WI: U.S. Department of Agriculture, Bureau of Department of Agriculture; 1961. 52 p. Entomology and Plant Quarantine; 1948. 4 p. Fitch, A. Catalogue of the known Homoptera of the State of Clements, J. R.; Fraser, J. W.; Stiell, W. M. Exploratory New York in 1851—4th annual report of the Regents of the studies of the compatibility of young red pine with sweet-fern. University of the State of New York on the State Cabinet of Inf. Rep. PS-X-6. Chalk River, ON: Canada Department of Natural History, 1851. In: 9th Report on the injurious and Forestry and Rural Development, Petawawa Forest Experi- other insects of the State of New York for the year 1892. Al- ment Station; 1968. 37 p. bany, NY: University of the State of New York; 1893. 393 p.

DeLong, Dwight M.; Severin, Henry H. P. Spittle-insect vec- Fowler, Richard F.; Wilson, Louis F.; Paananen, Donna tors of Pierce's disease virus: I. characters, distribution, and M. Insect suppression in Eastern Region National Forests: food plants. Hilgardia 19(ll):339-356; 1950. 1930-1980. Gen. Tech. Rep. NC-103. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station; 1986.

48 Giese, Ronald L.; Wilson, Louis. Diapause, and the embryo of Lyons, L. A. Damage to red pines by the Saratoga spittlebug. the Saratoga spittlebug. Wisconsin Academy of Science, Arts 1952 Bimonthly Prog. Rep. 8(6). Ottawa, ON: Canada and Letters 46:255-259; 1957. Department of Agriculture, Science Service, Division of Forest Biology. 1952: p. 1. Gruenhagen, R. H.; Riker, A. J.; Richards, C. Audrey. Burn blight of jack and red pine following spittle insect attack. Manthy, R. S.; Rannard, C. D.; Rudolph, V. J. The profit- Phytopathology 37:757-772; 1947. ability of red pine plantations. Agrie. Exp. Sta. Res. Rep. 11. East Lansing, ML Michigan State University; 1964. lip. Guilkey, P. C. Managing red pine for poles in lower Michigan. Sta. Pap. 57. St. Paul, MN: U.S. Department of Marshall, R. An experimental study of the water relations of Agriculture, Forest Service, Lake States Forest Experiment seedling conifers with special reference to wilting. Ecological Station; 1958. 21 p. Monographs 1:37-98; 1931.

Heyd, Robert Lewis. An evaluation of the impact of the McCaffery, K. R. Integrating forest and wildlife management Saratoga spittlebug, Aphrophora saratogensis (Fitch), on the in Wisconsin. In: Proceedings, 1970 Society of American growth of red pine, Pinus resinosa Ait. East Lansing, ML Foresters; 1970 October 12-13; Las Vegas, NV. Washington, Michigan State University; 1978. 80 p. Dissertation. DC: Society of American Forsters; 1970: 1-9.

Heyd, Robert L.; Murray, Ronald L.; Wilson, Louis F. Millers, Imants; Wilson, Louis F. Suppression of the Saratoga Managing Saratoga spittlebug Aphrophora saratogensis (Fitch) spittlebug, Aphrophora saratogensis (Fitch), with malathion in in pine plantations by suppressing sweet-fern. Northern Jour- Michigan pine plantations. Journal of Economic Entomology nal of Applied Forestry [In press]. 58(5):942-944; 1965.

Kelson, Walter E. Occurrence of Drosophila azteca in a spit- Milliron, H. E. Description of a new mymarid which tlebug mass (Diptera Drosophilidae). Pan-Pacific Entomologist parasitizes the eggs of the Saratoga spittlebug. Annals of the 40(2)k:116; 1964. Entomological Society of America 40(2):217-220; 1947a.

Kennedy, Patrick C; Wilson, Louis F. Understory vegetation Milliron, H. E. A new aphelinid egg parasite of the Saratoga associated with Saratoga spittlebug damage in Michigan red spittlebug, Aphrophora saratogensis (Fitch) (Hymenoptera, pine plantations. Canadian Entomologist 103:1421-1426; Aphelinidae). Proceedings of the Entomological Society of 1971. Washington 49(7): 193-197; 1947b.

Knull, Josef N. Observations on three important forest insects. Milliron, H. E. Results of field investigations on the use of Journal of Economic Entomology 25:1196-1199; 1932. DDT sprays for the control of the spittlebug, Aphrophora saratogensis (Fitch), in the Lake States—1946. Milwaukee, Latham, Robert P.; Millers, Imants. Aerial photography ap- WI: U.S. Department of Agriculture, Bureau of Entomology pears inadvisable for Saratoga spittlebug damage detection. and Plant Quarantine; 1949: Rep. 57 p. Minnesota For. Res. Notes 211. St. Paul, MN: University of Minnesota, School of Forestry; 1970; 2 p. Moore, Thomas Edwin. Evolution of the higher categories of Cercopidae, with a revision of the North American species of Linnane, J. P.; Osgood, E. A. Abnormally hot, dry weather Aphrophora (Homoptera). Urbana, IL: University of Illinois; apparently causes severe mortality of Saratoga spittlebug 1956. 175 p. Dissertation. nymphs in Maine. Research in the life sciences, vol. 23, no. 7. Orono, ME: University of Maine, Life Sciences and Ohmann, L. F.; Batzer, H. O.; Buech, R. R. [and Agriculture Experiment Station; 1967a: 1-3. others]. Some harvest options and their consequences for the aspen, birch, and associated conifer forest types of the Lake Linnane, J. P.; Osgood, E. A. Controlling the Saratoga spit- States. Gen. Tech. Rep. NC-48. St. Paul, MN: U.S. Depart- tlebug in young red pine plantations by removal of alternate ment of Agriculture, Forst Service, North Central Forest Ex- hosts. Tech. Bull. 84. Orono, ME: University of Maine, Life periment Station; 1978. 34 p. Sciences and Agriculture Experiment Station; 1976b. 12 p. Olson, Jeffrey T.; Lundgren, Allen, L. Equations for Linnane, J. P.; Osgood, E. A. Verrallia virginica (Diptera: estimating stand establishment, release, and thinning cost in Pipunculidae) reared from the Saratoga spittlebug in Maine. the Lake States. Res. Pap. NC-163. St. Paul, MN: U.S. Proceedings of the Entomological Society of Washington Department of Agriculture, Forest Service, North Central 79(4):622-623; 1977. Forest Experiment Station; 1978. 7 p.

49 Plakidas, A. K.; Smith, C. E. Diseases and insect pests of the Wilde, S. A. Forest soils and forest growth. Waltham, MA: strawberry in Louisiana. Ext. Circ. 113. Baton Rouge, LA: Chronica Botánica Co., 1946; 18: 241 p. Louisiana State Unviersity, Agricultural and Mechanical Col- lege; 1928. 34 p. Wilson, H. A.; Dorsey, C. K. Studies on the composition and microbiology of insect spittle. Annals of the Entomological Putman, William L. Notes on the bionomics of some Ontario Society of America 50:399-406; 1957. Cercopids (Homoptera). Canadian Entomologist 85:244-248; 1953. Wilson, Louis F. Life history and habits of a sweet-fern moth, Acrohasis comptoniella (Lepidoptera: Phycitidae), in Rudolph, P. O. Forest plantations in the Lake States. Tech. Michigan. Canadian Entomologist 102(3):257-263; 1970. Bull. 1010. St. Paul, MN: U.S. Department of Agriculture, Forest Service, Lake States Forest Experiment Station; 1950. Wilson, Louis F. A portable cage for insect study in the field. 171 p. Newsletter of the Michigan Entomological Society 16(3 & 4):1, 3. 1971a. Secrest, H. C. Damage to pine plantations in the Lake States by a spittle bug, Aphrophora saratogensis (Fitch). Milwaukee, Wilson, Louis F. Risk-rating Saratoga spittlebug damage by WL U.S. Department of Agriculture, Bureau of Entomology abundance of alternate-host plants. Res. Note NC-110. St. and Plant Quarantine; 1943; 50 p. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station; 1971b. 4 p. Secrest, H. C. Damage to red pine and jack pine in the Lake States by the Saratoga spittlebug. Journal of Economic En- Wilson, Louis F. Life history and habits of a leaf tier, Aroga tomology 37(3):447-448; 1944. argutiola (Lepidoptera: Gelechiidae), on sweet fern in Michigan. Canadian Entomologist 106: 991-994; 1974. Secrest, H. C. Experiments with airplane application of DDT spray to control the Saratoga spittle insect. Prog. Rep. Wilson, Louis F. Notes on the biology and parasitoids of the Milwaukee, WL U.S. Department of Agriculture, Bureau of sweet fern underwing (Lepidoptera: Noctuidae) in Michigan. Entomology and Plant Quarantine; 1946; 38 p. Great Lakes Entomologist 8(3): 145-153; 1975.

Severin, Henry H. P. Spittle-insect vectors of Pierce's disease Wilson, Louis F.; Heaton, George C. Notes on the life cycle virus: n. Life history and virus transmission. Hilgardia of Nemoria rubrifrontaria (Lepidoptera: Geometridae). Great 19(ll):357-382; 1950. Lakes Entomologist 7(4): 149-150; 1974.

Taylor, L. F. Aggregation, variance and the mean. Nature Wilson, Louis F.; Heyd, Robert L. Risk-rating and evaluation 189:732-735; 1961. survey for Saratoga spittlebug in red pine plantations. In: Forest insect and disease survey methods manual. Sec. 2.1.4. Thompson, F. Christian. Verrallia virginica Banks, a valid Davis, CA: U.S. Department of Agriculture, Forest Service, species (Diptera: Pipunculidae). Proceedings of the En- Forest Pest Management, Methods Application Group; 1978. tomological Society of Washington 79(4): 624-625; 1977. 12 p.

Tubbs, C. H.; Verme, L. J. How to create wildlife openings in Wilson, L.F.; Hobrla, S.L. A procedure for sampling nymphs northern hardwoods. St. Paul, MN: U.S. Department of of Saratoga spittlebug, Aphrophora saratogensis (Fitch) Agriculture, Forest Service, North Central Forest Experiment (Homoptera: Cercopidae), using percentages of sample units Station; 1972. 5 p. infested. Great Lakes Entomologist [In press]

Urie, D. H. Estimated groundwater yield following strip cut- Wilson, Louis F.; Heaton, George C; Kennedy, Patrick C. ting in pine plantations. Water Resources Research. Development and survival of Saratoga spittlebug nymphs on 7:1497-1510; 1971 alternate host plants. Great Lakes Entomologist 10(3):95-105; 1977. Walley, G. Stuart. The genus Aphrophora in America north of Mexico (Cercopidae, Hemipt.) Canadian Entomologist. Wilson, Louis F.; Kennedy, Patrick C. Suppression of the 60(8): 184-192; 1928. Saratoga spittlebug in the nymphal stage by granular baygon. Journal of Economic Entomology 61 (3):839-840; 1968. Whittaker, J. B. The biology of Pipunculidae (Diptera) parasitising some British Cercopidae (Homoptera). Proceedings Wilson, Louis F.; Kennedy, Patrick C. Control of Saratoga of the Royal Entomological Society of London (A). 44:17-24; spittlebug nymphs with systemic insecticides. Journal of 1969. Economic Entomology 64(3):735-737; 1971.

50 Wilson, Louis F.; Kennedy, Patrick C. Daily eclosión pattern of the Saratoga spittlebug, Aphrophora saratogensis (Fitch) (Homoptera: Cercopidae). Great Lakes Entomologist 7(3): 95-97; 1974.

Wilson, Louis F.; Millers, Imants. Suppression of Saratoga spittlebug with helicopter application of low- and high-volume malathion. Journal of Economic Entomology 59(6): 1456-1458; 1966.

Ziegler, H.; Huser, R. Fixation of atmospheric nitrogen by root nodules of Comptonia peregrina. Nature 199(4892):508; 1963.

51 Field Survey Forms

Use the following forms for:

1. Risk-rating Saratoga spittlebug 2. Nymphal appraisal survey of Saratoga spittlebug

Before risk-rating and sampling, read the section entitled Risk (page 38 of this publication). Photocopy the forms (front and back) for field use.

52 Saratoga Spittlebug Risk-Rating Survey

Field or Pianation No Date

County T R. _S._

Total acreage.

RISK-RATING

A Sweetfern B Other hosts C Nonhosts & bare ground Total 100%

A % % B % % C % % 100% 100% 100% 100% 100%

A % % B % %

C % % 0 10 20 30 40 50 60 70 80 90 100 100% 100% 100% 100% 100% PERCENT SWEET-FERN

A % % Use grid below to sketch planting B % % C % % 100% 100% 100% 100% 100%

A % % B % % C % % 100% 100% 100% 100% 100%

A % % B % % Acreage in each risk category: C % % 100% 100% 100% 100% 100% low moderate high _

53 Instructions for Saratoga Spittlebug Risk-Rating Survey

Unplanted land should be risk-rated between May and July for best results. Plantations should be risk-rated in May or early June so that nymphal surveys can be taken in June. Well-stocked stands of pine (that is, 600 or more trees/acre) taller than 3 m and with no visible symptoms of spittlebug injury are safe and need not be risk-rated. To risk-rate, you'll need a sketch map of the area, a clipboard, and a pencil. If this is an aerial survey, also read the instructions for risk-rating by air.

Risk-rating on the ground Risk-rating by air

Draw transect lines on planting sketch or map. Make 1. Estimate the low-, moderate-, and high-risk categories. You transects parallel and spaced 2 to 5 chains apart (1 chain = may have to rely mostly on the amount of sweetfem as the 66 ft. = 20 m). Use 5-chain spacing for unplanted land principal component. The risk is low for less than 15 per- with good visibility; use a spacing as close as 2 chains if the cent sweetfem; moderate for from 15 to 25 percent lateral view is inhibited by trees and/or terrain. sweetfem; and high for more than 25 percent sweetfem. If in doubt about any area, make ground spot-checks, espe- Walk transects. Stop every 1 to 2 chains to observe the cially when there are areas of high risk. Large amounts of ground cover. First, estimate the percentage of ground cover blueberry or blackberry may increase this risk. occupied by sweetfem foliage and then the percentage occupied by nonhosts (that is, grasses, sedges, lichens, 2. Draw boundaries of the categories on the sketch map. mosses) and bare ground. Then estimate the percentage of the other host plants (all other broadleaf herbs, ferns, small 3. Determine the acreage in each category. trees, etc.) or calculate this percent by subtracting the percentage of sweetfem and percentage of nonhosts from 4. To formulate a plan of action if moderate- or high-risk areas 100 percent. are present, read the Management Guidelines (page 44).

3. Use the risk-rating triangle to determine if risk is low, moderate, or high at each stop. Plot the percentage of sweetfem against the percentage of other hosts on the triangular graph at the right. The point at which the coordinates intercept on the graph will fall in one of the risk classes. For example, if you plot 10 percent sweetfem against 20 percent other hosts, the risk given by the graph is low. If, however, you plot 30 percent sweetfem against other hosts, the risk is high.

4. On the sketch map, place an L, M. or H at each stop to indicate low, moderate, or high risk, respectively.

5. After completing all observations, draw lines on the sketch or map that enclose areas of similar risk.

6. Estimate the acreage in each risk category.

7. To formulate a plan of action if moderate- or high-risk areas are present, read the Management Guidelines (page 44).

54 Saratoga Spittlebug Nymphal Appraisal Survey

Field or Plantation No. Date.

County T. _ _S._

Plot No

I. TREE-UNITS

A. Number of trees in 1/10-acre (66- by 66-ft) plot

B. Average no. of branch-whorls C. Average tree height (ft) per tree

1 1 6 2 2 7 3 3 8 4 4 9 5 5 10 Total Total Average Average

D. Calculate tree-units by multiplying A x B x C = tree-units per plot

11. NYMPHAL SURVEY Percent No. nymphs samples per 1/10-acre Take 50 systematic 1/10-milacre samples (1/10-milacre = infested plot 25 X 25 in. frame); record samples as infested (+) or not infested (-) 10 100 20 250 1 11 21 31 41 30 450 2 12 22 32 42 35 600 3 13 23 33 43 40 700 4 14 24 34 44 45 950 5 15 25 35 45 50 1100 6 16 26 36 46 55 1500 7 17 27 37 47 60 1800 8 18 28 38 48 65 2300 9 19 29 39 49 70 3100 0 20 30 40 50 75 4000 80 5900 85 9000

Count the number of infested (H-) samples

Multiply this value by 2 = percent samples infested.

Determine no. of nymphs per plot from chart nymphs per plot Nymphs per tree unit tree-units per plot

55 Instructions for Saratoga Spittlebug Nymphal 10. After taking 50 samples, count the pluses (-I-) and multiply Appraisal Survey by 2 to determine the percentage of samples infested with nymphs. The percentage of samples infested provides an estimate of the number of nymphs for the 1/10-acre plot. Saratoga spittlebug nymphs are best surveyed during the last 3 (See table in box on form.) weeks in June (for greatest accuracy). You will need a sketch map of the planting with risk areas delineated (from risk-rating 11. Calculate and record the nymphs per tree-unit by taking the field form), a clipboard and pencil, four nags or stakes, a number of nymphs per plot and dividing by the number of measuring pole (in feet), and a square sampling frame 25 in. by tree-units per plot. Nymphs per tree-unit gives the potential 25 in. (inside measure). damage level. 1. Survey the areas of high risk first. Survey moderate risk 12. Use this key to find action recommended after nymphal ap- areas if they qualify for control. praisal survey.^ 2. Determine the number of 1/10-acre (66- by 66-ft) plots needed according to the acreage at high risk. Oa) Nymphs per tree-unit less than 1.0—see no. 1 Ob) Nymphs per tree-unit 1.0 or more—see no. 8 Acres in high risk No. of plots la) Trees shorter than 10 ft—see no. 2 1-5 1 lb) Trees 10 ft or taller—see no. 4 6-10 2 11-20 3 2a) Nymphs per tree-unit less than 0.15—evaluate 21-40 4 □ again in 3 years 40 + 5 2b) Nymphs per tree-unit 0.15 or more—see no. 3

3. Establish 1/10-acre plots, demarcating the four corners 3a) Nymphs per tree-unit more than with flags or posts. Pace off the plot or use a 66-ft tape or □ 0.25—evaluate next year rope. 3b) Nymphs per tree-unit 0.15 to 0.25—evaluate □ in 2 years 4. Count the number of trees in the sample plot and record it on line A. 4a) Trees from 10 to 12 ft tall—see no. 5 4b) Trees taller than 12 ft—see no. 7 5. Determine the average number of whorls per tree and record it on line B. If the trees are the same age, you can 5a) Nymphs per tree-unit more than 0.15—see determine this easily from five trees. no. 6 5b) Nymphs per tree-unit 0.15 or less—no need to 6. Measure height (to nearest half foot) of 10 trees scattered □ reevaluate throughout the plot, calculate their average height, and record it on line C. 6a) Nymphs per tree-unit more than □ 0,25—evaluate next year 7. Calculate the tree-units for the plot by multiplying the 6b) Nymphs per tree-unit 0.15 to 0.25—evaluate number of trees (A) X average number of whorls (B) x □ in 2 years average tree height (C). Record this value in line D. 7a) Nymphs per tree-unit more than 8. Begin sampling nymphs at one corner of the plot. Drop the □ 0.40—reevaluate next year sampling frame and carefully examine all host plants within 7b) Nymphs per tree-unit 0.40 or less—no need to the frame for nymphs, which will be in spittlemasses. □ reevaluate When you find one live nymph, stop sampling and record the nymphs as a plus (+). If no nymphs are found after 8a) Nymphs per tree-unit 1.0 to 2.0—if there is examining all host plants, record the sample as negative □ flagging or noticeable degrade, control this (-). year; if not, reevaluate next year 8b) Nymphs per tree unit more than 2.0—control 9. Move to next sample and repeat. Take each sample about 5 □ this year or more feet apart to get 50 samples evenly spaced throughout the plot. Regularly stagger the sampling loca- iQiven near threshold values, use indicators of the previous year's feeding injury to help make a control decision. The previous year's feeding scars persist to add to the present tions so that some are taken in the lane between rows and year's injury; thus, use presence of feeding scars, flagging, and the previous insect others are taken close to the trees. evaluation, if available to decide if control is warranted.

56 Pesticide Precautionary Statement

Pesticides used improperly can be injurious to humans, animals, and plants. Follow the directions and heed all precautions on the labels.

Store pesticides in original containers under lock and key—out of the reach of children and animals—and away from food and feed.

Apply pesticides so that they do not endanger humans, livestock, crops, beneficial insects, fish, and wildlife. Do not apply pesticides when there is danger of drift, when honey bees or other pollinating insects are visiting plants, or in ways that may contaminate water or leave illegal residues.

Avoid prolonged inhalation of pesticide sprays or dusts; wear protective clothing and equipment if specified on the container.

If your hands become contaminated with a pesticide, do not eat or drink until you have washed them thoroughly. If you swallow a pesticide or get it in your eyes, follow the first-aid treatment given on the label, and get prompt medical attentíon. If a pesticide is spilled on your skin or clothing, remove clothing immediately and wash skin thoroughly.

Do not clean spray equipment or dump excess spray material near ponds, streams, or wells. Because it is difficult to remove all traces of herbicides from equipment, do not use the same equipment for insecticides or fungicides that you use for herbicides.

Dispose of empty pesticide containers promptly. Have them buried at a sanitary land-fill dump, or crush and bury them in a level, isolated place.

Note. This publication reports research involving pesticides. It does not contain recommendations for their use, nor does it imply that the uses discussed have been registered.

Some States have restrictions on the use of certain pesticides. Check your State and local regulations. Also, because registra- tions of pesticides are under constant review by the United States Environmental Protection Agency, consult your county agricultural agent or State extension specialist to be sure the in- tended use is still registered.

Back cover (top)—Sweeifern, the primary host of the Saratoga spittlebug. (bottom)—A spittlebug-infested plantation of red pine.