The Reemergence of Gypsy Moth

Gypsy moth larvae have red and blue spots and consume deciduous foliage until early July (bugwood.org). Over the past few years, the gypsy moth population in Massachusetts has steadily increased.  The summer of 2016 produced record numbers of these invasive leaf eating pests, defoliating over 100,000 acres across the state.

Since the devastating regional outbreaks of the 1980s, a soil-born fungus has helped keep gypsy moth populations managed naturally.  However, the extended dry weather and drought conditions throughout 2016 interfered with the prevalence of these beneficial fungi, causing caterpillar populations to skyrocket.

If the 2017 spring weather continues to be drier than normal, state environmental officials predict continued widespread gypsy moth caterpillar damage.  However, if there is a moderately wet spring season, a sufficient amount of fungal spores may be produced to again provide a natural control of gypsy moth caterpillars.

Gypsy moth overwinters in tan-colored, irregular shaped egg masses laid on the trunks of trees and contain 50 to 1500 individual eggs (K. Bernard).

Gypsy moths overwinter in tan-colored egg masses laid on the trunks of trees and begin hatching in early May.  Larvae grow and consume foliage until early July, then pupate.  The adult moths emerge in late July or early August, mate and lay eggs which lie dormant until the following spring, when the larvae feeding cycle begins again.

Homeowners can inspect their trees and property for egg masses in the fall or winter.

While most trees are tolerant of some partial defoliation, multiple years of defoliation, combined with other stress like drought, can lead to tree mortality.  Gypsy moth outbreaks are especially prevalent in areas dominated by oaks, a common tree in eastern and southern Massachusetts.

Protecting ornamental and shade trees in gypsy moth infested areas is important.  State forest health specialists are advising homeowners to work with Certified Arborists and licensed applicators to manage defoliation damage on valued landscape trees.

Gypsy moth outbreaks are especially prevalent in areas dominated by oaks, a common tree in eastern and southern Massachusetts (UMass).

We continue to monitor the situation in Greater Boston.  While outbreaks in our area have not been rampant, be aware of the potential and plan to prevent unnecessary damage to your important trees.  We recommend targeted control treatments in areas with past gypsy moth defoliation or confirmed insect presence.

If you have seen evidence of gypsy moths, caterpillars, eggs or your trees have experienced past defoliation, contact your Certified Arborist at BTSE to discuss management strategies to protect your property.