Interesting Insects Reported Recently:
Asiatic Oak Weevil: Cyrtepistomus castaneus is a ¼ to 1/3 inch long weevil that was first introduced into the US in 1933. It now occurs throughout much of the eastern US. Small, legless larvae overwinter near the roots of their host plants, and are in that life stage through the fall, winter, and spring. Pupation occurs as temperatures warm in the spring and adults emerge to feed on newly expanding leaves of oak and chestnut. Adults may emerge as early as May, with abundance peaking in late June and early July. Feeding by the Asiatic oak weevil starts on the margins of their host plant leaves and is sometimes so severe that everything is devoured except the major veins. Adults lay their eggs in the soil starting in July and continue into the fall. This non-native insect has become naturalized and can sometimes be seen feeding on its host plants. Images of the weevil and its feeding were submitted to UMass Extension by Dr. Jennifer Forman Orth, MA Department of Agricultural Resources, from Worcester, MA.
Dusky Birch Sawfly: Croesus latitarsus is a species of sawfly that feeds primarily on birch. Black, gray, Japanese white, paper, red, river, and yellow birch may all be suitable host plants. 1-2 generations occur per year, with the winter spent as a prepupa in a cocoon in the soil. Pupation occurs in the spring, with adult sawflies emerging in May. Eggs are laid and larvae are active roughly between April-May for the 1st generation and again in mid-July to mid-September in the 2nd generation. These sawfly caterpillars feed on the foliage of their hosts. Small trees may be defoliated; however, numbers of this species rarely reach levels where chemical intervention is necessary. Sawflies in this same genus are reportedly parasitized by Compsilura concinnata; however no natural enemies specific to the dusky birch sawfly have been reported. It is recommended that you leave these caterpillars alone if they can be tolerated in your landscape. Not only are they important wildlife themselves, but they may be food for other wildlife such as birds. These beautiful photos of the dusky birch sawfly were taken by Ryan Fawcett, MA Department of Conservation and Recreation, on river birch on 9/18/2023.
Current Nuisance Problems of Note:
Anyone working in the yard and garden should be aware that there is the potential to encounter deer ticks. The deer tick or blacklegged tick can transmit Lyme disease, human babesiosis, human anaplasmosis, and other diseases. Preventative activities, such as daily tick checks, wearing appropriate clothing, and permethrin treatments for clothing (according to label instructions) can aid in reducing the risk that a tick will become attached to your body. If a tick cannot attach and feed, it will not transmit disease. For more information about personal protective measures, visit: https://www.capecod.gov/departments/cooperative-extension/programs/ticks-bugs/.
The Center for Agriculture, Food, and the Environment provides a list of potential tick identification and testing resources.
*In the news: UMass Amherst has now been designated as the location for the New England Center of Excellence in Vector-Borne Diseases (NEWVEC). This CDC (Centers for Disease Control and Prevention) funded center will work to reduce the risk of vector-borne diseases spread by ticks, mosquitoes, and other blood-sucking insects or insect relatives in New England. For more information and to contact NEWVEC, visit: https://www.newvec.org/. To contact the center for more information about their Spring 2023 Project ITCH (“Is Tick Control Helping”), visit: https://www.newvec.org/itch .
- Mosquitoes: According to the Massachusetts Bureau of Infectious Disease and Laboratory Science and the Department of Public Health, there are at least 51 different species of mosquito found in Massachusetts. Mosquitoes belong to the Order Diptera (true flies) and the Family Culicidae (mosquitoes). As such, they undergo complete metamorphosis, and possess four major life stages: egg, larva, pupa, and adult. Adult mosquitoes are the only stage that flies and many female mosquitoes only live for 2 weeks (although the life cycle and timing will depend upon the species). Only female mosquitoes bite to take a blood meal, and this is so they can make eggs. Mosquitoes need water to lay their eggs in, so they are often found in wet or damp locations and around plants. Different species prefer different habitats. It is possible to be bitten by a mosquito at any time of the day, and again timing depends upon the species. Many are particularly active from just before dusk, through the night, and until dawn. Mosquito bites are not only itchy and annoying, but they can be associated with greater health risks. Certain mosquitoes vector pathogens that cause diseases such as West Nile virus (WNV) and eastern equine encephalitis (EEE).
Click here for more information about mosquitoes in Massachusetts.
EEE and WNV testing and tracking for this season began on June 12, 2023. The Massachusetts Department of Public Health tracks animal cases, human cases, and mosquito positive samples from traps from June through October in Massachusetts. The first West Nile Virus positive mosquito sample was collected on July 6, 2023, in the town of Brookline in Norfolk County, MA. Click here for more information.
As of September 21, 2023, 138 positive WNV mosquito samples have been collected in the state. See the previous link for specific locations.
As of 9/20/2023, 3 human cases of WNV have been reported in Massachusetts: https://www.mass.gov/news/state-health-officials-announce-first-two-human-cases-of-west-nile-virus-in-massachusetts.
The first eastern equine encephalitis (EEE) positive mosquito samples for 2023 were detected in Massachusetts as of 9/1/2023: https://www.mass.gov/news/state-public-health-officials-announce-seasons-first-eee-positive-mosquito-samples. As of September 21, 2023, 12 positive EEE mosquito samples have been collected in the state. See the previous link for specific locations.
There are ways to protect yourself against mosquitoes, including wearing long-sleeved shirts and long pants, keeping mosquitoes outside by using tight-fitting window and door screens, and using insect repellents as directed. Products containing the active ingredients DEET, permethrin, IR3535, picaridin, and oil of lemon eucalyptus provide protection against mosquitoes. Be aware that not all of these can be safely used on young children. Read and follow all label instructions for safety and proper use.
Click here for more information about mosquito repellents.
- Wasps/Hornets: Many wasps are predators of other arthropods, including pest insects such as certain caterpillars that feed on trees and shrubs. Adult wasps hunt prey and bring it back to their nest where young are being reared, as food for the immature wasps. A common such example are the paper wasps (Polistes spp.) who rear their young on chewed up insects. They may be seen searching plants for caterpillars and other soft-bodied larvae to feed their young. Paper wasps can sting, and will defend their nests, which are open-celled paper nests that are not covered with a papery “envelope”. These open-celled nests may be seen hanging from eaves or other outdoor building structures. Aerial yellow jackets and hornets create large aerial nests that are covered with a papery shell or “envelope”. Common yellow jacket species include those in the genus Vespula. Dolichovespula maculata is commonly known as the baldfaced hornet, although it is not a true hornet. The European hornet (Vespa crabro) is three times the size of a yellow jacket and may be confused for the northern* giant hornet (Vespa mandarinia). The European hornet is known to Massachusetts, but the northern giant hornet is not. European hornets have black, tear-drop shaped markings on their abdomens, but northern giant hornets do not. If you are concerned that you have found or photographed a northern giant hornet, please report it here: https://massnrc.org/pests/report.aspx. Recent articles in the news have homeowners concerned about a new invasive species of hornet that is closely related to the northern giant hornet. The yellow-legged hornet (Vespa velutina) has been detected in Georgia as of August 2023. The yellow-legged hornet is native to Southeast Asia and smaller than the northern giant hornet. There is concern that the yellow-legged hornet, if allowed to establish in the USA, could pose a threat to honeybee health. More information can be found here: https://agr.georgia.gov/yellow-legged-hornet . If you suspect you’ve seen the yellow-legged hornet in Massachusetts, take a photo and submit a report here: https://massnrc.org/pests/report.aspx .
Paper wasps and aerial yellowjackets overwinter as fertilized females (queens) and a single female produces a new nest annually in the late spring. Queens start new nests, lay eggs, and rear new wasps to assist in colony/nest development.Nests are abandoned at the end of the season. Some people are allergic to stinging insects, so care should be taken around wasp/hornet nests. Unlike the European honeybee (Apis mellifera), wasps and hornets do not have barbed stingers, and therefore can sting repeatedly when defending their nests. It is best to avoid them, and if that cannot be done and assistance is needed to remove them, consult a professional.
*Read more about the common name change for Vespa mandarinia.
Woody ornamental insect and non-insect arthropod pests to consider, a selected few:
Highlighted Invasive Insects & Other Organisms Update:
Spotted Lanternfly: (Lycorma delicatula, SLF) is a non-native, invasive insect that feeds on over 103 species of plants, including many trees and shrubs that are important in our landscapes. As of September 2023, the MA Department of Agricultural Resources (MDAR) has announced three additional populations of spotted lanternfly in Massachusetts. This brings the total locations of established populations of spotted lanternfly in Massachusetts to: Fitchburg, Shrewsbury, Worcester, Springfield, Holyoke, Agawam, and Southborough, MA.
As a reminder, there is no reason to be preemptively treating for this insect in other areas of Massachusetts. If you suspect you have found spotted lanternfly in additional locations, please report it immediately to MDAR here. If you are living and working in the above listed areas, please be vigilant and continue to report anything suspicious. Additionally, information about managing spotted lanternfly is provided in the Spotted Lanternfly Management Guide for Professionals, below.
For More Information:
From UMass Extension:
Spotted Lanternfly Management Guide for Professionals
*Note that management may only be necessary in areas where this insect has become established in Massachusetts and if high value host plants are at risk. Preemptive management of the spotted lanternfly is not recommended.
Spotted Lanternfly Fact Sheet
Check out the InsectXaminer Episode about spotted lanternfly adults and egg masses!
From the MA Department of Agricultural Resources (MDAR):
Spotted Lanternfly Fact Sheet and Map of Locations in MA
Spotted Lanternfly Management Guide for Homeowners in Infested Areas
*New*: Spotted Lanternfly Look-alikes in MA
*New*: Spotted Lanternfly Egg Mass Look-alikes
Box Tree Moth: staff with the Mass. Dept. of Agricultural Resources (MDAR) and the USDA have recently confirmed several instances of boxwood shrubs on Cape Cod that were infested with the invasive pest known as box tree moth (Cydalima perspectalis). The finds have all been in established plantings (2 years old or more). It is unclear how the moths were introduced to the area or how widespread this pest is; USDA is currently working to delimit the infestation.
The main host of box tree moth is boxwoods (Buxus spp.), though in their native range, the moths will also attack burning bush (Euonymus alatus) and a few other uncommon species, if boxwood is not available. The late-stage caterpillars cause significant defoliation and should be detectable now: check boxwoods for greenish brown caterpillars, 1 to 1.5 inches long, with black stripes running from head to tip, black heads, and long hairs scattered along the body. The caterpillars form webbing in the boxwoods to protect themselves, and in a heavy infestation this webbing fills up with visible clumps of frass pellets (waste material).
Box tree moths can cause complete defoliation of boxwoods, eventually killing entire shrubs. We encourage you to review the following fact sheet from the USDA to learn more about this pest, including how to recognize the adult moths, caterpillars, and eggs: 
Box Tree Moth Pest Alert
If you grow, sell, or install boxwoods, please inspect them for any signs of this pest, and report any finds to https://massnrc.org/pests/report.aspx
More information about box tree moth, including management options, is now available from UMass Extension at: https://ag.umass.edu/landscape/fact-sheets/box-tree-moth.
Elm Zigzag Sawfly: (Aproceros leucopoda) is a nonnative insect that originated in eastern Asia (Japan and certain regions of China). It is now invasive in Europe (2003) and North America. The elm zigzag sawfly has been found in Virginia (2021), Maryland, Pennsylvania, North Carolina, New York, and Vermont. In 2023, the elm zigzag sawfly was detected for the first time in a small, forested area of Berkshire and Hampden Counties in Massachusetts: https://www.mass.gov/news/dcr-announces-that-elm-zigzag-sawfly-has-been-confirmed-in-massachusetts. Significant defoliation of elm host plants was seen at the impacted locations. It is currently unclear how widespread the elm zigzag sawfly is in Massachusetts or how the infestation was introduced.
Female elm zigzag sawflies cause a tiny amount of damage to the edges of host plant leaves as they lay their eggs. Tiny scars are formed as a result of female egg laying. Eggs hatch and young sawfly caterpillars (the most destructive life stage of the insect) begin their characteristic zig-zag patterned feeding. These zig-zag shaped notches in the leaf can extend 5-10 mm into the leaf from the edge. Multiple caterpillars can feed on a single leaf. Entire leaves can be completely stripped, leaving only the veins behind. Heavily infested trees can suffer partial or complete defoliation.
If you suspect you have found elm zigzag sawfly in Massachusetts, please report it to Nicole Keleher (Massachusetts Department of Conservation and Recreation, Forest Health Program), Nicole.Keleher@mass.gov, or to the MA Dept. of Agricultural Resources at https://massnrc.org/pests/report.aspx.
More information about the elm zigzag sawfly, including management options, is now available from UMass Extension at: https://ag.umass.edu/landscape/fact-sheets/elm-zigzag-sawfly.
- Southern Pine Beetle: Dendroctonus frontalis has been collected in traps in Massachusetts and other parts of New England in recent years. Historically, the southern pine beetle has been native to the southeastern United States, however its range is moving northward due to warming winters and climate change. The Massachusetts Department of Conservation and Recreation (DCR) Forest Health Program, has announced that they have detected the first pocket of southern pine beetle killed trees (pitch pine, Pinus rigida) in Massachusetts on Nantucket. This is the first observation of this species killing trees in the state. An active infestation of southern pine beetle was found killing trees in July and MA DCR is working with the property owner to determine next steps and potential management options at the site. If you believe you have detected southern pine beetles in trees in Massachusetts, please contact Nicole Keleher, MA DCR Forest Health Director, at: nicole.keleher@mass.gov. More information about southern pine beetle is also available from MA DCR at https://storymaps.arcgis.com/stories/b60f63199fa14805a8b9f7c82447a25b .
The southern pine beetle (SPB) undergoes complete metamorphosis (is holometabolous) with four life stages: egg, larva, pupa, and adult. Adults are dark red/brown to black in color and 1/16 – 1/8” in length. Eggs are white and larvae are crescent-shaped with a dark red/brown head and a white body. Four larval instars are present, with pupa being bright white. The adult is light brown in color prior to drying and hardening and becoming darker in color. Female beetles select suitable host trees and release chemical pheromones to attract male mates. She will penetrate the bark and begin creating a gallery where she is joined by the male and mates. Early attacks to the tree may be “pitched out” by the resin defenses of the tree. The pheromones produced by the females and the volatile chemicals expressed by the stressed host plant attract additional males and females. If tree defenses can be overcome, females will colonize beneath the bark, creating S-shaped galleries. The inoculation of the tree with a blue stain fungus as well as other fungi occurs with colonization of southern pine beetle, however, it is the act of "mass attack" by the insects themselves which leads to tree mortality. Entomocorticium spp. symbiotic fungi are associated with southern pine beetles and the immature larvae feed on this fungus. Females may lay up to 160 eggs in their lifetime and development can take as little as 26 days in warmer climates. In the South, 3-9 generations of SPB have been observed to occur per year. In NY, 3-4 generations have been observed on Long Island. Current Massachusetts temperatures should keep the number of generations per year to the lower end of this range.
Southern pine beetle can be detected most easily by the presence of popcorn-sized pitch tubes on the outer bark of trunks and branches. Pitch tubes can range in color from white to red. They can occur from ground level to high in the canopy of the tree. Exit holes (about 1/16” in diameter) can be observed in the bark from emerging adults. S-shaped galleries can also be observed by peeling back any bark that may be falling off the tree. Brown-orange frass (excrement) that looks like wood shavings is found packed within the galleries. By the time foliage fades from green to yellow to brown, the infestation may be advanced. The presence of certain checkered or clerid beetles can also indicate high populations of southern pine beetle, as these checkered beetles prey upon SPB. Southern pine beetle prefers trees damaged by lightning strikes or fire. In the southeastern part of the insect's range, southern pine beetle is not known to preferentially attack drought stressed or chronically stressed trees. Trees under 15 years of age or 2 inches in diameter may be seldom attacked.
- Asian Longhorned Beetle: (Anoplophora glabripennis, ALB) Look for signs of an ALB infestation which include perfectly round exit holes (about the size of a dime), shallow oval or round scars in the bark where a female has chewed an egg site, or sawdust-like frass (excrement) on the ground nearby host trees or caught in between branches. Be advised that other, native insects may create perfectly round exit holes or sawdust-like frass, which can be confused with signs of ALB activity.
Adult Asian longhorned beetles typically begin to emerge from trees by July 1st in Massachusetts. It is important to take photographs of and report any suspicious longhorned beetles to the Asian Longhorned Beetle Eradication Program phone numbers listed below.
The regulated area for Asian longhorned beetle is 110 square miles encompassing Worcester, Shrewsbury, Boylston, West Boylston, and parts of Holden and Auburn. If you believe you have seen damage caused by this insect, such as exit holes or egg sites, on susceptible host trees like maple, please call the Asian Lonbghorned Beetle Eradication Program office in Worcester, MA at 508-852-8090 or toll free at 1-866-702-9938.
Report an Asian longhorned beetle find online or compare it to common insect look-alikes here.
Emerald Ash Borer: (Agrilus planipennis, EAB) has been detected throughout much of Massachusetts and it was recently detected for the first time in Barnstable County. A map of these locations across the state is provided by the MA Department of Conservation and Recreation at https://storymaps.arcgis.com/stories/b60f63199fa14805a8b9f7c82447a25b.
This wood-boring beetle readily attacks ash (Fraxinus spp.) including white, green, and black ash and has also been found developing in white fringe tree (Chionanthus virginicus) and has been reported in cultivated olive (Olea europaea). Signs of an EAB infested tree may include D-shaped exit holes in the bark (from adult emergence), “blonding” or lighter coloration of the ash bark from woodpecker feeding (chipping away of the bark as they search for larvae beneath), and serpentine galleries visible through splits in the bark, from larval feeding beneath. It is interesting to note that woodpeckers are capable of eating 30-95% of the emerald ash borer larvae found in a single tree (Murphy et al. 2018). Unfortunately, despite high predation rates, EAB populations continue to grow. However, there is hope that biological control efforts will eventually catch up with the emerald ash borer population and preserve some of our native ash tree species for the future.
- Jumping Worms: Amynthas spp. earthworms, collectively referred to as “jumping or crazy or snake” worms, overwinter as eggs in tiny, mustard-seed sized cocoons found in the soil or other substrate (ex. compost). Immature jumping worms hatch from their eggs by approximately mid-to-late May. It may be impossible to see them at first, and it may be more likely that jumping worms are noticed when the first adults begin to appear at the end of May and in June. It is easy to misidentify jumping worms (ex. mistake European earthworms for jumping worms) if only juveniles are found. In August and September, most jumping worms have matured into the adult life stage and identification of infestations is more likely to occur at that time of year.
For More Information, see these UMass Extension Fact Sheets:
Earthworms in Massachusetts – History, Concerns, and Benefits
Jumping/Crazy/Snake Worms – Amynthas spp.
A Summary of the Information Shared at UMass Extension’s Jumping Worm Conference in January 2022
Invasive Jumping Worm Frequently Asked Questions (Over 70 Questions and their Answers)
Tree & Shrub Insect Pests (Native and Invasive):
- Ailanthus Webworm: Atteva aurea (formerly A. punctella) is a tropical ermine moth from the family Attevidae. While they may be referred to as tropical, apparently the moths themselves can tolerate much colder temperatures than their original host plants. Prior to 1784 when tree of heaven (Ailanthus altissima) was introduced into Philadelphia, PA, the ailanthus webworm was restricted to southern Florida and points south. It would appear that this restriction in distribution was due to the distribution of their original host plants in the genus Simarouba. Once tree of heaven’s range extended from the north to the south including Florida, the moths were able to move northward on the newly available and suitable host plant. Larvae of this moth feed almost exclusively on tree of heaven in the northern parts of its expanded range. Occasionally, these caterpillars will defoliate tree of heaven, but not to the extent that they could provide any form of control of this invasive tree (on younger plants, sometimes caterpillars can completely defoliate the trees and strip the bark off of small branches). Larvae cluster together in a loose web. Larvae of the ailanthus webworm have five white longitudinal lines on an olive-brown colored base with sparsely hairy bodies. Caterpillars are found in the late summer. Larvae pupate within their webs; moths emerge, mate, and then lay their eggs on the outside of the webs. Multiple overlapping generations can occur per year.
- Andromeda Lace Bug: Stephanitis takeyai is most commonly encountered on Japanese Andromeda. Eggs are tiny and inserted into the midveins on the lower surface of the leaf and covered with a coating that hardens into a protective covering. 5 nymphal stages are reported. Nymphs are different in appearance from the adults, often covered with spiky protrusions. 3-4 generations per year have been observed in New England, with most activity seen between late-May into September (starting at approximately 120 GDD’s, Base 50°F). Both nymphs and adults can be seen feeding on leaf undersides. Adults have delicate, lace-like wings and what appears to be an "inflated hood" that covers their head. Adults are approximately 1/8 of an inch long. Arrived in the US in Connecticut in 1945 from Japan (Johnson and Lyon, 1991).
Can cause severe injury to Japanese andromeda, especially those in full sun. Mountain Andromeda (Pieris floribunda) is highly resistant to this pest. Like other lace bugs, this insect uses piercing-sucking mouthparts to drain plant fluids from the undersides of the leaves. Damage may be first noticed on the upper leaf surface, causing stippling and chlorosis (yellow or off-white coloration). Lace bug damage is distinguished from that of other insects upon inspecting the lower leaf surface for black, shiny spots, "shed" skins from the insects, and adult and nymphal lace bugs themselves.
A first sign of potential lace bug infestation is stippling or yellow/white colored spots or chlorosis on host plant leaf surfaces. Lace bugs excrete a shiny, black, tar-like excrement that can often be found on the undersides of infested host plant leaves. Flip leaves over to inspect for this when lace bug damage is suspected.
Mountain Andromeda (Pieris floribunda) is considered to be highly resistant to this insect and can be used as an alternative for such plantings, along with other lace bug-resistant cultivars. Consider replacing Japanese Andromeda with mountain andromeda as a way to manage for this pest. Natural enemies are usually predators, and sometimes not present in large enough numbers in landscapes to reduce lace bug populations. Structurally and (plant) species complex landscapes have been shown to reduce azalea lace bug (Stephanitis pyrioides) populations through the increase of natural enemies
- Fall Home-Invading Insects: Various insects, such as ladybugs, boxelder bugs, seedbugs, and stink bugs will begin to seek overwintering shelters in warm places, such as homes, throughout the next couple of months. While such invaders do not cause any measurable structural damage, they can become a nuisance especially when they are present in large numbers. While the invasion has not yet begun, if you are not willing to share your home with such insects, now should be the time to repair torn window screens, repair gaps around windows and doors, and sure up any other gaps through which they might enter the home.
- Hickory Tussock Moth: Lophocampa caryae is native to southern Canada and the northeastern United States. There is one generation per year. Overwintering occurs as a pupa inside a fuzzy, oval shaped cocoon. Adult moths emerge approximately in May and their presence can continue into July. Females will lay clusters of 100+ eggs together on the underside of leaves. Females of this species can fly, however they have been called weak fliers due to their large size. When first hatched from their eggs, the young caterpillars will feed gregariously in a group, eventually dispersing and heading out on their own to forage. Caterpillar maturity can take up to three months and color changes occur during this time. These caterpillars are essentially white with some black markings and a black head capsule. They are very hairy, and should not be handled with bare hands as many can have skin irritation or rashes (dermatitis) as a result of interacting with hickory tussock moth hairs. By late September, the caterpillars will create their oval, fuzzy cocoons hidden in the leaf litter where they will again overwinter. Hosts whose leaves are fed upon by these caterpillars include but are not limited to hickory, walnut, butternut, linden, apple, basswood, birch, elm, black locust, and aspen. Maple and oak have also been reportedly fed upon by this insect. Several wasp species are parasitoids of hickory tussock moth caterpillars.
- Mimosa Webworm: Homadaula anisocentra was first detected in the United States in 1940 in Washington, D.C. on its common namesake host plant. Originally from China, the mimosa webworm is primarily a pest of honeylocust (Gleditsia triacanthos; including thornless cultivars). This insect is found throughout the eastern and midwestern states and California. In the warmer parts of its range in the United States, it has historically heavily attacked mimosa where it grows. Adults are moths that are silvery gray in color with wings interrupted by black dots. Moths are approximately 13 mm in size (wingspan). Fully grown larvae reach up to 16 mm long and are variable in color from gray to brown with five longitudinal white stripes. Once mature, the caterpillars move to the bark scales of their host plants and find sheltered places to pupate. They may also be found in the leaf litter beneath host plants, pupating in a cocoon. Pupae are yellowish brown, 6 mm long, and encased in a white cocoon. Adult moths may emerge in early-mid June and lay gray eggs on the leaves of their hosts that turn a rose color just prior to hatch. Eggs hatch and feeding caterpillars web the foliage together, feeding within the web for protection. Larvae may be found feeding together in groups, in which case larger and aesthetically displeasing webs may be created. If disturbed, the larvae may move quickly and can drop from the web on a line of silk. A second generation of moths may occur, with pupation happening and adults emerging by August in warmer locations. In New York and New England, it is likely that this second generation emerges in September and any offspring may be killed with the winter. In the warmest parts of this insect's introduced range in the United States, three generations may be possible per year.
The larvae (caterpillars) of this insect tie the foliage of their hosts together with silken strands and skeletonize the leaves. Injury to host plant leaves may be noticeable by early July in Massachusetts. Foliage can appear bronzed in color from the feeding. Webbing usually begins at the tops of trees. An entire tree may become covered in the webs created by these caterpillars. So much webbing can often make it difficult to assess the extent of the defoliation or damage caused on an individual host.
Certain cultivars of honeylocust may vary in their susceptibility to this insect. Gleditsia triacanthos 'Sunburst' was highly susceptible to attack in Indiana. Cultivars such as 'Moraine', 'Shademaster', and 'Imperial' may be less susceptible - however, they are still able to be fed upon by this insect, so annual monitoring may be necessary.
- Redheaded Pine Sawfly: Neodiprion lecontei can be an important native pest of ornamental, forest, and plantation pines. Jack, shortleaf, loblolly, slash, red, and other two and three-needle pines are suitable hosts and occasionally others in proximity to these. This insect overwinters as a prepupa in a cocoon in the leaf litter near is hosts. Pupation occurs in the spring and adults emerge a few weeks later. Some prepupae have delayed emergence, which can occur 2 or 3 years later. Females lay over 100 eggs in rows of slits in the edges of several needles. Egg laying can take place without mating, with unfertilized eggs producing males. Fertilized eggs produce males and females. Larvae hatch in a month and feed gregariously. Eventually, they drop to the ground to spin overwintering cocoons. Historically in New England, a single generation occurred per year. In more southern parts of its range, 2-3 generations may occur annually. Anecdotally, as the growing season and winters warm in New England due to climate change, it seems a second generation of this insect is possible and may already be occurring. Natural enemies include rodent predators of the pupae as well as diseases of the larvae.
Concerned that you may have found an invasive insect or suspicious damage caused by one? Need to report a pest sighting? If so, please visit the Massachusetts Introduced Pests Outreach Project.
Reported by Tawny Simisky, Extension Entomologist, UMass Extension Landscape, Nursery, & Urban Forestry Program
