You Are Here: Management Updates 2004 Archive December 9, 2004

Date: December 9, 2004
Category: Insects
Subject: Winter Moth

I have received reports of large numbers of winter moths flying in southeastern Massachusetts over the last few days. I know very little about winter moths, but talked with some of the people in Joe Elkinton's lab (an insect ecologist at UMass who specializes in forest insects). They told me that winter moth (Operophtera brumata) is one of two species of moths that have been wreaking havoc in southeastern Massachusetts, including Cape Cod, for the last three or four years. The winter moth is an introduced species that may have come from Europe, where it is a serious pest.

The insect is remarkably adapted to our climate. The moths emerge in late November or early December. Only the males can fly. Females climb trunks of trees and lay eggs on the trees. Caterpillars (which are a kind of "inchworm") hatch out as early as late March. They tunnel into buds, especially flower buds of apples, crabapples, cherry, maples, oaks, and various flowering trees. The caterpillars are quite mobile, and move from one bud to another readily, so they can cause severe damage in the spring. They also will feed on foliage.

There is nothing to be done at this point. Moth flights may continue through much of December. (Believe it or not, some of the UMass research being conducted this year is being compromised because the insect populations are too heavy!) There may be some options that can be used to target the eggs in late winter or the young caterpillars as they become active in the spring.

In a recent conversation, Joe Elkinton told me that there is a parasitic fly (a tachinid fly) that has reduced winter moth populations significantly in two different locations (one was Nova Scotia). He is in the processing of collecting some of these flies and hopes to be able to release some of them this spring in southeastern Massachusetts as the caterpillars begin to emerge. He notes that the flies have provided excellent levels of control in the past, and there is reason to be optimistic that they will do so here as well. However, he also cautions that it will take three to five years for the flies to become established. So for the short term, we will need to minimize stress on the ornamental trees that are under attack.

An excellent fact sheet from the UMass Extension Urban Landscape and Nursery program is available that provides more information, including control strategies. See it at:

http://www.umassgreeninfo.org/fact_sheets/defoliators.html

In addition, other information pops up in a cursory search of the web - simply type in "winter moth" on your search engine.

Submitted by: Dr. Pat Vittum