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Forest Pest Fact Sheet Massachusetts Dept. of Conservation and Recreation Forest Health Program Gypsy

Background Photo: Dieder Descouens The gypsy moth has been a costly and persis- Pupae: Around the third week of June, cater- tent problem in Massachusetts since its intro- pillars will find a safe, protected location to duction in 1869. Despite control efforts by pupate. Pupae are red- federal and state agencies, gypsy moth popula- dish brown and 0.75- 1 tions continue to defoliate our forests here in in. long. Pupation takes Massachusetts and expand their range in the 10-15 days to complete. U.S. Photo: USDA APHIS PPQ Adult: Adult will emerge in mid-July. Life Cycle and Identification Female moths are larger (2-2.5 in.), white with Gypsy moths have one generation per year. brown chevron markings, and flightless. Male During their lifecycle they complete four dis- moths are smaller (1.5 in.) tinct life stages: egg, larvae (), pu- and light brown with dark pae, and adult (moth). brown chevron markings. Egg: Female adult moths lay Males will fly to females to egg masses by early August on mate and complete their trees, houses, outdoor furni- lifecycle. Photo: USDA APHIS PPQ ture, or cars where they will overwinter. Egg masses are Gypsy Moth Impacts buff colored, approximately 1- Damage to trees and forests by gypsy moths 1.5 inches long ,and contain primarily occurs through defoliation by the Photo: Charlie Burnham, Mass DCR 100-1000 eggs. caterpillar life stage. Dense feeding popula- Larvae: Small, mostly black tions can consume all the leaves on a tree, de- (~1/16 in long) will emerge in early May: exact foliating entire stands. The preferred host tree timing depends upon climate conditions (~145 are deciduous , maple, birch, pop- -200 GDD). It is at this small size that the lar, willow, apple, and hawthorn. Other, less gypsy moth disperse by wind, until they land preferred deciduous trees and even conifers, on a host tree where like white or eastern hemlock, will be at- they begin to feed on tacked by gypsy moths when there are large foliage. Caterpillars outbreaks. Typically, a healthy deciduous tree will continue to feed can survive one complete defoliation event, and progress through because they have enough energy reserved to 5-6 instars until they produce new foliage in the same growing sea-

Photo: Milan Zubrik, Forest Research Institute reach a final size up to son. However, multiple years of defoliation or 2.5 inches. Larger caterpillars can be identi- additional stress can cause deciduous tree fied by their hairy bodies and five pairs of blue mortality. Conifers will die after only one dots and six pairs of red dots down their back. heavy defoliation event. Population Dynamics Applications should be done by licensed applica- Across Massachusetts, tors with the specialized equipment required to gypsy moth density can completely coat a tree’s leaves. Btk should be fluctuate greatly from applied directly to foliage soon after caterpillar year to year. Gypsy emergence where it will be consumed during moths have cyclical peri- feeding. Btk is most effective in young caterpil- ods of small persistent lars and will not be effective on large caterpil- populations and large lars. Treatments should typically be applied at outbreaks. Population 90-400 GDD. Often, by the time caterpillar feed- trends are primarily ing is noticeable on a tree, it is too late to treat. driven by climate condi- This is why it is important to check for egg tions and the balance of Photo: Rich Anair, Mass DCR masses before emergence and look for the small natural predators and disease. Predation from caterpillars in early May. small mammals, , and , as well as, parasitic infection from flies and wasps regulates Many commonly recommended treatment op- small populations. tions are not effective in decreasing gypsy moth population or minimizing damage to trees. Under certain conditions, gypsy moths can be These include burlap strips, duct tape bands, or significantly impacted by disease. Nucleo- moth traps. polyhedrosis virus (NPV) is a wilt disease that causes high mortality in caterpillars and If trees have been defoliated by gypsy moth, as- when populations have been maintained high sess and monitor tree health and recovery. Trees density in an area. The introduced fungus Ento- may require additional watering, fertilizing, or mophaga maimaiga (EM) causes high mortality mulching to promote in during both periods of low and high density refoliation. Avoid ad- infestations, but requires ditional stressors, such specific moisture and as, mechanical or temperature conditions chemical damage or to effectively spread and soil compaction. infect the caterpillars. Finally, an important EM has kept gypsy moth effort in management populations from reach- is to minimize gypsy ing large outbreak stages moth spread. Egg Photo: Felicia Andre, Mass DCR since the late 1980’s. masses can be located However, dry conditions on more than just trees; common locations in- in Massachusetts can clude cars, trucks, storage and moving contain-

Photo: Charlie Burnham, Mass DCR lead to large outbreaks ers. Anytime after eggs are laid in August, check due to lack of EM fungal success. for hidden egg masses to avoid spreading gypsy Management Strategies moths. Viable egg masses will be firm to the There are several steps Massachusetts residents touch and have no holes. can take to protect their trees from mortality For more information: caused by gypsy moths. The first step in gypsy moth management is assessing and monitoring DCR Forest Health Program Phone: (413) 253-1798 x204 the population. Be aware of the caterpillars seen Website: http://www.mass.gov/dcr/forest- feeding in the spring, the presence and location health of adult moths, and the abundance of egg masses. MDAR Program Phone: (617)626-1700 The recommended treatment for Website: http://www.mass.gov/eea/ gypsy moth is spp. agencies/agr// kurstaki (Btk) or another biological pesticides.