Cover Photos: Top - H. crocea larvae James Kruse (Entomologist), Ken Zogas, Nicholas Lisuzzo and Steve Swenson (Biological Science Technicians), USDA Forest Alder-feeding Bottom Left - A M. pulveratum larva Service, Alaska Region, State and Private Forestry. Bottom right - An E. ovata larva andnumber sawflies), of characteristics: and the same all insect insert family, a Tenthredinidae.single egg through These the leafsawflies cuticle share into a Sawflies of Alaska Alder-feeding Sawflies of Alaska the leaf tissue using a strong, somewhat Additional information on this insect can be obtained from In recent years, Alaskan alders have been ‘saw-like’ ovipositor; larvae are all external your local Alaska Cooperative Extension office, Alaska State increasingly assaulted by a variety of insects, leaf feeders; all pupate in the ground in Forestry office, or from: pathogens and abiotic agents. Recent an excavated chamber where they spin Forest Health Protection examples are: vast areas of generalized a cocoon or line the chamber with silk; State and Private Forestry foliage browning in interior, south-central, USDA Forest Service 11305 Glacier Highway and southwestern Alaska; a six year for thin-leaf alder (Alnus incana subsp. Juneau, Alaska 99801-8626 outbreak of the generalist, native, hardwood andtenuifolia finally, all exhibit a strong preference Phone: (907) 586-8883 defoliator, Sunira verberata in Katmai all small, compact insects, and even though National Park; extensive defoliation by the they are wasps,) as a primary to the casual host. observerThe adults they are Forest Health Protection State and Private Forestry Eriocampa USDA Forest Service ovata, in the Anchorage area beginning in included in the same insect family as wasps 161 East 1st Avenue, Door 8 invasivethe mid-1990’s; alder woolly a wide sawfly, variety of canker moreand bees, often they resemble are neither flies. venomous,Although they nor are Anchorage, AK 99501 fungi, most commonly Valsa melanodiscus, capable of stinging. Phone: (907) 743-9449 causing premature leaf death, stem dieback, Life History Forest Health Protection stem death, and whole clump mortality State and Private Forestry at local and landscape levels throughout USDA Forest Service 3700 Airport Way Fairbanks, Alaska 99709 Monsoma pulveratum, TheEgg-laying green alderis in progress sawfly is in the mid-May, first of the at Phone: (907) 374-3758 Alaska;primarily and in finally,south-central severe defoliationAlaska. Further, by a three sawflies to emerge in the spring. new,more exotic than one sawfly, of these agents are frequently http://www.fs.fed.us/r10/spf/fhp found acting in concert—several species of The U.S. Department of Agriculture (USDA) prohibits defoliators for example, or insect/pathogen discrimination in all its programs and activities on the basis interactions. of race, color, national origin, sex, religion, age, disability, political beliefs, sexual orientation, or marital or family status. (Not all prohibited bases apply to all programs.) Persons with in Alaska are: Eriocampa ovata, the alder disabilities who require alternative means for communication The three primary,Hemichroa alder-feeding crocea, sawfliesthe striped of program information (Braille, large print, audiotape, etc.) , should contact USDA’s TARGET Center at (202) 720-2600 (voice Monsoma pulveratum and TDD). woolly sawfly; To file a complaint of discrimination, write USDA, Director, alder sawfly; and Office of Civil Rights, Room 326-W, Whitten Building, 1400 theare nonnativeEuropean greeninsects, alder while sawfly. the striped Both Independence Avenue, SW, Washington, DC 20250-9410, Prepared by Leaflet the green alder and alder woolly sawflies or call (202) 720-5964 (voice and TDD). USDA is an equal United States Department of Forest Service R10-TP-154 Figure 1. Extensive alder defoliation and opportunity provider and employer. Agriculture Alaska Region October 2012 alderorder, sawfly Hymenoptera is a native, (bees, circumpolar wasps, ants, dieback along the Susitna River, Alaska. sawfly. All three are in the same insect approximately 15°C, when the alder leaves burrows into woody material, and spends target. Many of the infested alders lie within the winter in stumps, broken branches and an area normally excluded from operational down logs. This behavior is believed to be insecticide spray programs because of its aremid just to late beginning June. Egg-laying to flush. Both commences alder woolly ecological sensitivity. immediately and continues for several account for their early emergence in the and striped alder sawfly adults emerge from Homeowners do not normally encounter weeks as new adults emerge. Green alder spring. a b unique to this genus of sawfly, and may problems with these insects. If an individual Detection and Damage is concerned about a small group of infested alders on their property, effective control sawfly egg deposition differs markedly from can be achieved either through hand-picking feeding is quite obvious. Early in the season, the two other sawfly species. Egg deposition of the larvae from the leaves or treatment is on the underside of the leaf along and as active feeding begins, numerous small for green alder sawflies is on the upper leaf The damage to the host alders due to sawfly with a strong jet of water. Repeating these holes appear in the leaves as the small surface, alder woolly sawflies egg deposition activities several times throughout the egg deposition is along the leaf petiole. c d larvae feed. This results in a characteristic summer may be required. into the midrib, and striped alder sawflies “shotgun” appearance. In time, these small species is 1-2 weeks. Upon hatching, green Figure 2. a- H. crocea egg sites. feeding voids coalesce into larger holes. Embryonic sawfly development for all three b- M. pulveratum egg sites. c- E. ovata egg Ultimately, the larvae consume all the soft leaf surface. All three species feed openly sites. d- An alder leaf after larval feeding. tissue between the leaf veins leaving behind alder sawfly larvae migrate to the lower only the stouter veins and leaf midrib. The the soft leaf tissue, leaving behind only the covering is shed, exposing a very pale green shrub takes on a thin, brownish appearance easily seen from the ground or aerially. on the leaves, consuming (in most cases) all instar (stage of larval development), the a b larvae feed gregariously, while the alder Alder, like most hardwood tree species, yellowish- to greenish- brown with two Figure 3. a. An adult M. pulveratum leaf veins and midrib. Striped alder sawfly is able to withstand several seasons of body.black Thelateral larvae stripes of striped on either alder side sawfly of their are b. Overwintering sites for M. pulveratum larvae However, in high larval density situations, it body. They are quite robust, though slightly severe defoliation suffering nothing more woolly and green alder sawflies feed singly. shorter in length at full development than than growth loss and possibly branch isone not species uncommon might tobe find found five on or an more individual green larval development is complete, the woolly severe defoliation can reduce its nitrogen alder. It is possible to have two or even all contribution to the soil by more than 70% CAUTION: Pesticides can be injurious to humans, alder sawfly larvae per leaf. At times, only alder woolly or green alder sawflies. When dieback. With the case of alder however, domestic animals, desirable plants, and fish or other three species feeding on the same plant, or ground and burrow into the soil beneath annually. Alder mortality has been observed, wildlife—if they are not handled or applied properly. even on the same leaf. in other defoliator outbreaks, after 5 or more Use all pesticides selectively and carefully. Since alderthe leaf and litter. striped There, alder they sawflies excavate drop a small to the consecutive seasons of severe defoliation. approved uses of a pesticide may change frequently, Appearances differ markedly among the chamber 1-4.5 cm beneath the soil surface. it is important to check the label for current approved The larvae then enter a pre-pupal state and Control Options and legal use. Follow recommended practices for the colored to very pale green upon hatching. remain in this condition throughout the disposal of surplus pesticides and pesticide containers. Since thin-leaf alder is primarily a riparian Mention of a pesticide in this publication does not As they grow and develop, they change to winter. In spring, when the ground begins to larvae. Green alder sawfly larvae are creamy- species and an important component constitute a recommendation for use by the USDA, a vibrant bluish-green. Full grown larvae warm and reach the threshold temperature of many salmon spawning streams, nor does it imply registration of a product under can exceed 18 mm in length. Alder woolly for each species to continue development, Federal Insecticide, Fungicide, and Rodenticide Act, as the pre-pupae change to pupae, and after amended. Mention of a proprietary product does not constitute an endorsement by the USDA. like covering on their bodies. As they grow, implementationdeleterious effects of onsawfly aquatic control insects measures as well sawflythis covering larvae becomessecrete a denser.white, waxy, In their hair- last some time, they emerge as adults. By would be difficult. Some insecticides have contrast, the green alder sawfly typically as the terrestrial insects they specifically