What is Winter Moth?
Winter Moth (Operophtera Brumata) is a moth that was introduced to the area from Europe through Nova Scotia. It is an invasion species that causes damage to trees, perennials and shrubs. Locally, the hardest hit areas include coastal Massachusetts, Connecticut and Maine. It has also been seen in the Pacific Northwest.

This causes injury to perennials, trees and shrubs when larve (caterpillars) tunnel into buds to feed. Larve continue feeding as they move from bud to bud. Defoliation occurs as older larve feed in the expanding leaf clusters. Trees most at risk are Maple, Oak, Cherry, Basswood, Ash, White Elm, Apple, Crabapple and Blueberry. Larve can also drop from your trees onto your perennials and shrubs.

What do you need to watch for?
Do you remember seeing moths flocking around your outside lights last year? Those were the culprits and their offspring will be arriving this spring!

Moths in their adult stage emerge from the soil in November. Moth activity generally extends into January. This is when they can be seen flying  around your lights. After mating, the females deposit eggs in bark crevices, under bark scales and under lichen, etc. These egg clusters look like tiny individual barrels that are tightly packed together. There are no control options for the adult stages of these moths. Both males and females die soon after mating and egg disposition.

Egg hatch occurs in the spring when temperatures reach 55 degrees F. Winter Moth larve are pale green caterpillars often referred to as loopers or inch worms. After egg hatch, larve crawl up tree trunks and begin to penetrate leaf buds where they begin to feed. You will notice that the buds and part of the leaves are eaten. Larve feed through mid June when they migrate to the soil for pupation and overwintering.

What can you do for Winter Moth Control?

  • An effective Integrated Pest Management (IPM) program that consists of both maintaining tree health and chemical treatments is necessary to promote tree vigor and suppress populations of the insect.
  • Trees exposed to good cultural practices are better able to withstand Winter Moth outbreaks. Mulch and fertilizer according to soil analysis and irrigation during dry or drought periods are all excellent cultural treatments that improve tree health.
  • Tree banding has proven to be a good control mechanism.
  • Properly timed chemical spray treatments are highly effective for controlling large outbreaks.