Home and Horticultural Borers Common Kansas Species

The term “borers” applies to a wide range of insects as they feed on inner bark and sapwood tissues. Destruction whose immature stages generally develop within host plants. of these tissues hinders formation of new wood and essen- Although insects feeding on foliage pose a minimal threat tially girdles branches and trunks, resulting in dead branches to health and vigor of woody plants (because auxiliary buds and trunks beyond zones of destruction. The most prevalent can produce new foliage), borers feed unseen beneath bark, flatheaded borers in Kansas are thebronze birch borer (Fig. 3) destroying irreplaceable cambial and wood tissues. Insect and the flatheaded appletree borer (Fig. 4) borers are commonly classified according to taxonomic families within larger orders. Orders with the most borer Roundheaded Borers (Family: Cerambycidae) species are Coleoptera (beetles) and Lepidoptera (moths). Cerambycids are a large group of wood-boring beetles. Hymenoptera (bees and wasps) and Diptera (flies) each have Longhorned beetles vary greatly in size, shape and coloration. borer species, but they are few and rarely cause major damage. Roundheaded borers may initially feed on outer tissues When the term “trees” is used in this publication, it should but eventually burrow deeper into wood, where feeding or be understood to include woody shrubs. tunneling activities structurally weaken trees and shrubs. Examining break points in downed limbs often provides Coleopterans (Beetles) evidence of roundheaded borer feeding damage. The two most recognized families of borer beetles are Many common Kansas wood borers are roundheaded Buprestidae and Cerambycidae, commonly referred to as borers. These include thecottonwood borer (Fig. 5) — prob- metallic wood borers and longhorned wood beetles, respec- ably the most widely recognized borer in Kansas because of tively. Legless larvae distinctively indicate their borer status. its imposing size and unusual coloration. The relatively long- Buprestids are sometimes called flatheaded borers for their lived adults (one month) feed on tender leaf and bark tissues. distinctly enlarged and flattened thoraxes, with abdominal Most female beetles eventually move to tree bases, forming segments that are generally constricted and flattened (see shallow pits below the soil line. Larvae burrow mainly in Fig. 1, p. 4). Cerambycid larvae are called round-headed roots, but galleries can extend slightly above ground level. borers for their round thoraxes and abdomens (Fig. 2). A Adults emerge through holes in either location. Smaller, third prominent family of borer beetles are Scolytidae, whose younger trees (one to two years) are most susceptible to larvae typically create gallery systems beneath bark where cottonwood borer damage. Beetles can girdle small branches, mature larvae pupate. Newly emerged beetles bore directly giving young trees a scrawny, broken and defoliated appear- through bark, creating randomly spaced emergence holes ance. Larger, established trees can absorb more damage but ranging from bird-shot-sized to BB-sized and earning the may show leafless, smaller branches high in canopies. name “shothole borers.” Poplar borer (Fig. 6) beetles tend to select larger, estab- lished trees. Elm borers (Fig. 7) are attracted to weakened Flatheaded Borers (Family: Buprestidae] trees. Larvae tunnels through bark disrupting the flow of Buprestids are especially damaging to newly transplanted nutrients and water. As larvae grow larger, damage increases, trees lacking established root systems. Beetles deposit eggs including girdling and dead branches. Attacks usually occur in bark cracks and crevices and over a period of years, causing gradual decline and eventual are especially attracted to wound death. Pole borers (Fig. 8) are indiscriminate feeders that areas (e.g. pruning cuts or mower deposit eggs in wound areas (usually around tree bases) or and string-trimmer damage at previous galleries. Some beetles emerge in late summer and tree bases). After boring through seek new hosts. Others do not emerge, but rather mate and bark, young larvae become estab- lay eggs in old galleries. Pole borers seldom attack injury-free lished in the sapwood, forming trees with healthy bark. broad serpentine galleries (right) Larval galleries

Kansas State University Agricultural Experiment Station and Cooperative Extension Service Mulberry borer (Fig. 9) beetles emerge from mid-May to girdling branches before and during the egg-laying period. mid-June, living for several weeks. Tilehorned prionus (Fig. After girdling, branches remain attached to the tree by a thin 10) beetles begin appearing in mid-summer. Females deposit core (below right) until their weight, aided by wind, causes eggs in soil at tree bases. Larvae enter roots and feed on outer breakage. By the time branches snap off, twig girdlers are bark before moving into larger roots. As these are hollowed no longer present. Although larger mature trees may have a out, trees’ structural integrity is compromised. Smaller roots ragged appearance, damage is considered minimal. In smaller are also consumed, decreasing anchorage or tree stability nursery trees or devel- and leading to general decline and eventual death. Ash oping landscape trees, and privet borer (Fig. 11) beetles are present from May to excessive branch drop August, laying eggs in both healthy and dying hosts. Larvae may result in unusual pack frass behind them as they tunnel into wood, leaving no forking and tree external signs of their activity. deformities, rendering Girdled branch Despite its name, the red oak trees unmarketable and borer (Fig. 12) also attacks all aesthetically diminished. white oak species. Adults emerge Examining cut ends of branches on from June through August. the ground helps determine whether Damage in the first year of the squirrels or twig girdlers are causing two-year life cycle is difficult to damage. Squirrels gnaw through detect, but enlarged holes in the branches, leaving ragged edges and bark and stains from oozing sap causing them to immediately drop to "Buzz-saw" cut (right) alert people to borers’ the ground. Twig girdlers do not com- presence in the second year. pletely sever branches, but rather make Established trees seem to tolerate Red oak borer damage neat “buzz-saw” cuts around central stalks (above right). borer activities, and wounds heal over time. However, borer damage Shothole Borers (Family: Scolytidae) downgrades harvested and milled lumber. Some scolytid beetles are designated shothole borers. 1 1 Thelocust borer (Fig. 13) is most abundant in September, They are small ( ⁄16 to ⁄8 inch long) and seldom seen. Close when it often feeds on goldenrod and ragweed pollen during inspection of sick or recently dead trees reveals the small daylight. As the day ends, beetles return to locust trees shotholes that confirm their presence. People assume trees and deposit eggs. Damaged trees or trees in nutrient-poor are killed by these beetles and their larvae when, in fact, soils or eroded sites tend to be more susceptible to locust scolytids are attracted to stressed trees with minimal defenses borer damage. Trees planted on good sites and thrifty, older, and deliver the final death blow. While most are not consid- dominant trees usually survive locust borer attacks. ered economically important, some destructive species have a major impact on forests and the lumber industry. A recent Three borer species are commonly encountered emerging report by the Kansas Department of Agriculture listed 52 from firewood stored indoors or crawling on stacked outdoor scolytid species in Kansas. Three species are perhaps the most firewood. Thepainted hickory borer beetle (Fig. 14) closely important and frequently encountered. resembles the locust borer beetle, but is active only in spring and has a wider host range. Logs cut the previous winter are Eastern ash bark beetles (Fig. 19) create egg galleries in their preferred egg-laying sites. Redheaded ash borer (Fig. boles, limbs and larger branches of weakened trees. Two gen- 15) beetles often are attracted to newly transplanted trees erations per season are normal in Kansas. Watersprout growth struggling to become established, as well as young, stressed at tree bases attracts second-generation beetles, which later trees with minimal sapwood. Usually, borer damage becomes move to node or bud areas to create overwintering chambers. evident when trees are cut into lumber and larval galleries Damaging outbreaks are historically sporadic and unpredict- make it unmarketable. Thebanded ash borer (Fig. 16) beetle able, making insecticidal control impractical. Applications after emerges in early spring. Its normal one-year developmental the fact are of little or no value. cycle may lengthen to several years under less than ideal Smaller European bark beetles (Fig. 20) seek healthy conditions (e.g., if infested materials are sawed, stored and trees to feed or weakened or diseased trees to breed. They dried out). are the primary carrier of the fungal pathogen responsible Theivory marked beetle (Fig. 17), also called the four- for Dutch elm disease. Beetles carry fungal spores that they marked ash borer, may have a two-year life cycle, but one transmit when feeding in twig crotches of healthy trees. By report claims a prolonged life history in dry wood; one beetle midsummer, initial symptoms of Dutch elm disease may be apparently emerged from a 40-year-old birch bookcase. evident on scattered branches. Foliage wilts, turns yellow and eventually dies, leaving foliage on dead branches dry Thetwig girdler (Fig. 18) is responsible for twigs lit- and brown. It may take several years for the tree to reach a tering the ground in late September and October. Beetles dramatically rapid final demise. Communities once fought feed on tender bark prior to mating. Fertile females begin elm loss by implementing sanitation practices to eliminate  breeding sources, applying insecticide to healthy trees, and Cultural Practices For Borer Management destroying underground root grafts. There is, however, little that homeowners personally can do to prevent tree loss. A And Prevention tree service may apply insecticide against each of two beetle Borers are considered secondary pests. They are often generations, but this may not avert the disease. attracted to weakened and stressed hosts. In Kansas, the primary stress factor is drought, especially when coupled Theeastern fivespined ips (Fig. 21) prefers recently felled with extremely hot weather. Other factors contribute to pine trees and slash for egg-laying, but also attacks trunks and moisture stress. Around construction sites, excavation may branches, particularly in stressed and weakened trees. This severely damage and reduce root systems of established trees species likely produces several generations annually in Kansas. retained for landscaping. Heavily compacted soils restrict Insecticide applications against these beetles are impractical re-establishment of pruned or damaged roots, as well as due to their unpredictable occurrences. Sanitation practices, newly transplanted trees’ root development. Compacted soils such as removing and disposing of dead trees and debris, will are less able to absorb and store water. Excessive numbers of eliminate sources of beetles. trees and shrubs can compete for moisture. When adequate Lepidopterans (Moths) moisture is available small borer larvae do not survive water surging through tree vascular elements. They are “sapped out” Two families of lepidopterans with the most familiar borer or “drowned.” species are Sesiidae and Cossidae. Sesiids are commonly called clearwing moths for their transparent wings. Another common name is wasp moths for the wasp-like coloration and patterns of some species, their ability to hover, and their Tips to ensure tree health and vigor buzzing noises. Sesiid moths are active during daylight and • Select proper tree varieties. Extension foresters or local vary in size. Wingspans range from 1⁄5 to 3/4 inch. Larvae have nursery employees can recommend varieties best suited for a typical caterpillar appearance, are white, and reach 11/3 inches different areas in Kansas, as well as placement or exposure. in length. Although several dozen sesiid species are considered • Consider buying locally produced trees. Nurseries pests of trees, shrubs, vines, and herbaceous plants, only a few know which tree and shrub species do well in their areas. receive attention in control guides. • Select trees after noting their general health, vigor and A common Kansas species is officially known as both the conformation. Avoid bargain trees, which may have unde- ash borer and the lilac borer (Fig. 22) for its primary hosts. sirable attributes that decrease prices or marketability. Moth emergence and activity typically begin in mid-April • Look for signs of borer activities. Leafless or dead and end in late June. Egg-laying moths are attracted to wound branches can indicate ongoing problems. Closer inspec- sites, but also will deposit eggs on trunks and larger limbs. tion, especially at a tree base, can reveal borer exits. Initial flight activities can be monitored with traps containing Cracked and separated bark also hints at borer damage. artificial clearwing borer pheromone to attract male moths. • Prepare sites to give transplanted trees the best op- Control is best achieved by applying insecticides to trunks and portunity to successfully take root and thrive. Extension larger branches seven to 10 days after moth capture. publications detail steps to prepare trees for transplanting, as well as proper planting procedures and techniques. The carpenterworm moth and leopard moth are the two prevalent Cossidae species in Kansas. Carpenterworm moths • Give constant attention and care to help trans- (Figs. 23, 24) are especially common. They likely have a two- plants overcome transplant shock. Water for plant uptake is critical. Moist soil allows new roots to gain year life cycle, emerging from April through July. Each moth a foothold and expand, providing additional sur- may produce up to 1,000 eggs. Galleries may be 6 inches long face area for water uptake as well as anchorage. and quite wide to accommodate larvae, which move back and • Water and fertilize newly transplanted or young forth between galleries and tree exteriors, expelling sawdust trees properly to stimulate establishment and growth. and frass. Tunneling may cause structural weakening of larger This is needed beyond initial years of establishment, limbs, resulting in breakage. Carpenterworm damage reduces especially during hot or dry periods (including winter). wood quantity and lumber quality. • Place tree wraps around trunks of transplanted or young Leopard moths (Fig. 25) attack more than 100 species trees to protect against egg laying. Replace or repair wraps of trees and woody shrubs if hosts have wood of sufficient if tears occur. Use them for several years, but change diameter to support the large larvae. Moth emergence begins them intermittently to avoid constricting trunk growth. in May and extends through August. Each female produces • Prune or remove and dispose of sick, dead, or fallen 400 to 800 eggs, deposited singly or in small clusters in bark branches and limbs to deal with established borers. Con- crevices or beneath bark scales. Larvae hatch in 10 days. If sider removing seriously ailing trees, borer-weakened trees they initially bore into small stems, they may outgrow their and dead trees, all of which could support future borers. confines and leave to seek another feeding site. The slow- • Consider insecticides as a preventative tool against insect developing larvae overwinter twice before moths emerge. borers.

 Fig. 1: Flatheaded borer Fig. 2: Roundheaded larva borer larva Fig. 3: Bronze birch borer Fig. 4: Flatheaded Agrilus anxius Gory appletree borer Chrysobothris femorata (Olivier)

Fig. 7: Elm borer Fig. 5: Cottonwood borer Fig. 6: Poplar borer Saperda tridentata Olivier Plectrodera scalator (Fabricius) Saperda calcarata Say

Fig. 8: Pole borer Parandra brunnea (Fabricius) Fig. 9: Mulberry borer Fig. 10: Tilehorned prionus Dorcaschema wildii Uhler Prionus imbricornis (Linnaeus)

Fig. 12: Red oak borer Fig. 13: Locust borer Fig. 11: Ash and privet borer Enaphalodes rufulus (Haldeman) Megacyllene robiniae (Forster) Tylonotus bimaculatus Haldeman

(Pictures not to scale)

 Fig. 15: Redheaded ash borer Fig. 16: Banded ash borer Fig. 14: Painted hickory borer beetle Neoclytus acuminatus (Fabricius) Neoclytus caprea (Say) Megacyllene caryae (Gahan)

Fig. 17: Ivory marked beetle Fig. 19: Eastern ash bark beetle Fig. 18: Twig girdler Eburia quadrigeminata (Say) Hylesinus aculeatus Say Oncideres cingulata (Say)

Fig. 21: Eastern fivespined ips Fig.20: Smaller European elm bark beetle Figure 22: Ash/lilac borer Ips grandicollis (Eichoff) Scolytus multistriatus (Marsham) Podesia syringae (Harris)

Fig: 23: Male carpenterworm moth Fig. 24: Female carpenterworm moth Fig. 25: Leopard moth Prionoxystus robiniae (Peck) Zeuzera pyrina (Linnaeus)

(Pictures not to scale)

 Borer name / hosts Description Warning Signs Life Cycle Bronze birch borer Olive to black-brownish; narrow, flat- Dead branches in treetops. 1 year; overwinter as larvae. Birch, esp. European white tened, and 1/4 to 7/16 inches long. Wide range of larval stages birch results in continuous adult presence from late spring through summer. Flatheaded appletree borer Broad, oval, flattened beetles, 1/4 to 5/8 Readily apparent trunk damage to 1 year; overwinter as larvae. Indiscrimate attacks on many inches long. new transplants. Pupation in spring and tree species early summer. Most beetle activity in May, but occurs through mid-fall. Cottonwood borer 1 to11/2 inches long, black and white Frass exuded on collars and ex- Varies from 1 year (in young Cottonwood, poplar coloration. Entirely black long antennae. posed brace roots of mature trees, trees) to 2 years (in older but damage often only evident trees); but some adults after trees fall. Girdling may give appear every year. Adults scrawny, broken, defoliated ap- emerge from late June pearance to nursery trees. through mid-August in Kansas. Poplar borer 3/4 to 11/4 inches long; grey, speckled by Oozing sap; frass and woodshav- Reportedly 2 to 5 years, Poplar, cottonwood cover of small dark spots. Readily vis- ings at gallery entrances. although not known in ible, somewhat orange markings. Kansas.

Elm borer 3/8 to 1/2 inch long; grey fuzz, reddish Reddish frass exuding from open- 1 year. New larvae bore into Elm orange stripe (back ridges and wing ings in bark crevices; girdling outer bark and then inner covers) and slanted crossbars on outer and dead branches as larvae size bark and sapwood, where wings; two black dots on each side of increases. they overwinter. Beetles back, two on each wing case and one typically appear from May on each wing end. through July.

Pole borer Broad and flattened; shiny mahogany Most activity is in heartwood. Frass 3 to 4 years. New beetles Indiscriminate attacks on color; males 3/4 inch long with promi- is packed in galleries, so damage form in late summer; some many tree species nent mandibles, females 1/2 to 5/8 inch signs generally not evident. Wind emerge and seek new hosts, long with smaller mandibles. damage to weakened trees (includ- while others remain in gal- ing downed trees) may be first leries to mate and lay eggs. evidence. Mulberry borer 5/8 to 7/8 inch long; cylindrical front tho- Sap ooze from niches for egg-lay- 1 year. Larvae overwinter Mulberry, Osage orange rax gives it “necked” appearance; coat ing; fine frass from small larvae, and beetles emerge mid- of fine gray hairs conceals dark brown coarse and fibrous from older lar- May to mid-June and live body; small round bare spots give vae. Dieback on branches and part several weeks. Egg-laying wing covers pitted appearance. of crown during initial attacks. continues into early July.

Tilehorned prionus Broad, shiny, dark reddish-brown; 11/4 No direct signs. Excavating around 3 to 5 years. Beetles begin Oak, pecan, hickory, poplar, to 13/4 inches long; distinctive tiled larger roots may expose oval exit appearing in mid-summer. Osage orange, cottonwood, antenna extend from one-third to holes for larvae. Females lay eggs in soil at and tree fruit species (apple, halfway down wing covers. base of trees. Larvae bore peach, plum, etc.) into roots but later return to soil to build pupation chambers. Ash and privet borer Elongated and somewhat flattened. Close inspection may reveal sap 2 years. Beetles present May Ash, privet, elm, hickory, Mostly brown with three light creamy oozing from site of larval penetra- to August. black walnut, some poplar or yellowish spots along wing covers. tion. First signs may be killing of and birch species larger limbs.

 Borer name / hosts Description Warning Signs Life Cycle Red oak borer Fine, downy cover of light brown or Difficult to detect in first year 2 years. Adults emerge Red oak, white oak tan, blotched and darkened as it wears because of small entry-hole size June-August; larvae over- away with age. Females 15/16 inches (more enlarged in second year). winter in inner bark, then long. Males have 11/2-inch bodies, with Staining from oozing sap may sig- move into sapwood the antennae exceeeding body length. nify borer presence (see Fig. 12). following year. Large larvae overwinter twice.

Locust borer Bright yellow bands on black back- Sap oozing from larval entrance 1 year. Beetles appear in late Black locust and its cultivars ground. Straight lines across front holes in spring, along with increas- summer, early fall. Larvae of thorax and top of wing covers; ingly evident amounts of frass. overwinter in inner bark, W-shaped on wing covers. then move into sapwood and heartwood the next year.

Painted hickory borer Looks similar to locust borer, but active Most often found in firewood in 1 year. Beetle emergence Ash, black walnut, hackberry, only in spring. and around homes. and early egg-laying in mulberry, oak spring allows larvae to develop quickly and pupate over winter.

Redheaded ash borer Elongated, tapered beetle, 1/4 to 3/4 inch Young trees may develop slowly, 1 year. Beetle emergence Ash, hickory, walnut, oak, long. Front of thorax is round and has with some branch dieback. Estab- varies from May to Septem- birch, maple, dogwood, fine, rusty-reddish hairs. Four distinct lished trees may show some exit ber. Larvae enter sapwood redbud, hackberry, black lines of fine yellow hairs traverse wing holes in trunks, but most attacks within several weeks and locust, honeylocust, Osage covers. Front legs noticeably shorter. are undetectable. Damage is most enter pupal stage by late orange, lilac, pear, cherry, evident when trees are felled for winter or early spring. plum, peach, apple, elm, lumbering. sweet gum

Banded ash borer 3/8 to 3/4 inch long. Dark brown to black Beetle may emerge from or crawl 1 year to several years (un- Cut ash, hickory and elm logs with band of cream-colored hairs on on firewood, both indoors and out. der less-than-ideal condi- front of thorax and four bands on tions). Pupation occurs in each wing cover, with first two almost fall and beetles overwinter, circular. then emerge in early spring.

Ivory marked beetle 1/2 to 3/4 inch long. Ivory-colored spots No early warning signs. Not certain. 2 years to Ash, hickory, oak, maple, at base and middle of each light-brown perhaps many years in dry honeylocust, elm, bald wing cover. wood. cypress

Twig girdler 5/8 to 3/4 inch long. Primarily greyish First visual evidence often is 1 year, with beetle activity Elm, pecan, hackberry are brown, but some specimens have branches with dead brown leaves. from August to October. preferred hosts. Also found lighter ash-grey band on wing covers. Snapped-off branches on ground Slow development means in apple, pear, peach, plum, Small, scattered tufts of yellowish or show neat, “buzz-saw” cuts around overwintering larvae, but dogwood, oak, honeylocust, golden bristles on wing covers. central stalk. accelerates in spring and poplar, maple summer. Pupation by August and September.

Eastern ash bark beetle 1/16 to 1/8 inch long. Primarily dark brown Close inspection reveals small Rapid larval development Ash with flat, grayish white scales. Dark dia- shotholes dotting dead branches. (2 months) provides two mond pattern on front of thorax; her- generations per year. ringbone pattern across wing covers. Beetles can overwinter and emerge directly in early spring to start new cycle.

 Borer name / hosts Description Warning Signs Life Cycle Smaller European elm bark 1/8 inch maximum. Black front thorax and No early warning signs; appear- 6 weeks from egg to adult beetle dark reddish-brown wing covers. Stout ance of shotholes after infestation. beetle; two generations Elm spine projecting beneath abdomen. per year in Kansas. Larvae overwinter and pupation/ beetle emergence occur in early spring. Eastern fivespined ips 1/8 to 3/16 inch long. Dark reddish-brown. No early warning signs; appear- Although confirmation is Mostly felled pine trees Five prominent spines project rearward ance of shotholes after infestation. needed, there are appar- and slash, but weakened from wing covers. ently several generations or stressed pines may be per year in Kansas. affected

Ash borer or lilac borer 1 to 11/2 inch wingspan. Appearance Sap with a fine frass inclusion ooz- 1 year. Moth emergence Ash, lilac, privet varies; forewings typically opaque and ing from larvae entrance burrows, from mid-April to late June. blackish with tinges of red or chestnut eventually becoming chunky frass. Overwintering larvae. brown; newly emerged moths black in Moth exit holes above entrances. front, reddish brown in back with series of yellow hair tufts encircling abdomen. Older moths generally darker.

Carpenterworm Females: 3-inch wingspans with light Sap spots with finely mixed frass 2 years in Kansas. Moths Primarily elm and green ash, speckles on grey and black wings; early; as infestation advances, emerge April through July. but also other tree species plump, fuzzy, grey abdomens. Males: sap stains are larger and wood 2-inch wingspans, darker appearance chips and frass are expelled from (black head and thorax, black wings entrance holes. with orange highlights on hind wings).

Leopard moth Wings and thorax white with black Broken twigs, wilted yellow foliage 2 years. Moths emerge May More than 100 tree and spots. 3-inch wingspan for females, at first. Dead brown foliage and to August. Larvae overwin- shrub species 2 inches for males. broken branches in upper canopy ter twice. later.

Author Robert Bauernfeind, Entomologist All photos by Robert Bauernfeind except "Red oak borer damage" on p. 2 (courtesy of Kim Bomberger, Kansas Forest Service) and Fig. 26 (courtesy of Ashraf El-Sayed, Canterbury Research Centre)

Brand names appearing in this publication are for product identification purposes only. No endorsement is intended, nor is criticism implied of similar products not mentioned. Publications from Kansas State University are available on the World Wide Web at: www.oznet.ksu.edu Contents of this publication may be freely reproduced for educational purposes. All other rights reserved. Robert Bauernfeind. Borers: Common Kansas Species, Home and Horticultural Pests, MF -2735. Kansas State University, October 2006.

Kansas State University Agricultural Experiment Station and Cooperative Extension Service MF-2735 October 2006 K-State Research and Extension is an equal opportunity provider and employer. Issued in furtherance of Cooperative Extension Work, Acts of May 8 and June 30, 1914, as amended. Kansas State University, County Extension Councils, Extension Districts, and United States Department of Agriculture Cooperating, Fred A. Cholick, Director.