Winter Moth Damage Predicted to be Up in 2010

UMass Extension is predicting an increase in damage caused by winter moth caterpillars this spring. As reported in this article in the Brockton Enterprise, Deborah Swanson, Extension educator for Plymouth County, is expecting defoliation of trees by winter moth caterpillars to be significant in southeastern Massachusetts. This is based on data from UMass indicating that adult moth populations were greater in 2009 than in previous years, meaning more eggs were laid and more caterpillars will hatch this spring. For information about winter moth, including tips on how to protect your trees, check out UMass Amherst's 2010 winter moth preview.

It's that time of year again: Winter Moths are here

Male winter moth	Female winter moth

Throughout Eastern Massachusetts, residents are reporting seeing small brown moths flying around at night, flocking to porch lights and other light sources. There are a few different species that are in this fall/winter burst of activity, with the most numerous appropriately named "winter moth." Winter moths (Operophtera brumata) are a European species thought to have been introduced to the USA around the year 2000. Since then, they have become quite common in Cape Cod, the rest of Southeastern Massachusetts and have continued to spread westward.

Expect to continue to see these insects through December, particularly when nighttime temperatures remain above freezing. Moths you see in flight are always males; female winter moths are practically wingless and spend their days on tree trunks, house foundations, or other surfaces, waiting for a mate. While winter moths can be a nuisance when they cluster around homes in large numbers, they do their real damage as small green caterpillars, attacking cherry, crabapple and other trees in early spring and often completely defoliating them.

As with most invasive species, the winter moth invasion is not a simple one. Some of the moths active right now are actually fall cankerworm moths (Alsophila pometaria), a native species that also defoliates trees, and whose populations occasionally grow large enough to become a nuisance. There is also a native relative of the winter moth, the Bruce spanworm moth (Operophtera bruceata), which looks so similar to winter moth that scientists need a microscope to tell them apart. The Elkinton Lab at UMass Amherst has found evidence that the introduced winter moths have been hybridizing with Bruce spanworm moths, and is now studying the impact this could have on the native species as well as on efforts to establish a biological control for winter moths in our state.

To learn more about winter moths, including how to prevent tree damage, check out these web pages:

• Our winter moth fact sheet
  
• Recommended treatments from UMass Extension
  

Winter moth caterpillars

If you've noticed an onslaught of little green caterpillars devouring the leaves on your trees, you are not alone - winter moth caterpillar season has kicked into high gear. We are receiving many reports from our report-a-pest form of this pest attacking trees, particularly in the eastern and southeastern part of the state. Many of you seeing this damage now will remember the moth in its adult form, as it is one of few moths in flight during the winter months.

While there are a variety of treatments to protect trees from winter moth and other defoliating caterpillars, one of the most promising management techniques is the effort to develop a biological control for this pest. Biologists at UMass Amherst have been working on just such a program, but it will take several years for the biocontrol to establish, so expect winter moths to continue to be a problem. More information about winter moth is available on our fact sheet.

Winter moth mix

Male winter moth	Female winter moth

With nighttime temperatures about to rise above freezing again over the next few days, expect to see even more winter moths hovering around your porch lights. Entomologists are saying that winter moth populations are on the rebound this year, with populations larger than we've seen for a while. The insects you'll see fluttering about are all males. The females are practically wingless and spend their days on tree trunks or other surfaces, waiting for a male to mate with. Adult moths are mainly a nuisance right now - they do all of their damage in the caterpillar stage, as tiny green larvae that can be found munching on the leaf buds of cherry, crabapple and other trees in early spring.

True winter moths (Operophtera brumata) are thought to have been introduced to the USA from Europe around 2000. As with most invasive species, the winter moth situation is not a simple one. The Elkinton Lab at UMass Amherst has found evidence that the introduced moths have been hybridizing with a similar-looking but less common native species, the Bruce spanworm moth (Operophtera bruceata). The lab continues to study this phenomenon and the impact it could have on the native species as well as on efforts to establish a biological control for winter moths in our state.

Winter moth resources:

• Our winter moth fact sheet
  
• Recommended treatments from UMass Extension
  

Flies on the Attack

If you are in Wellesley, MA tomorrow, keep your eyes peeled for swarms of tiny but powerful (and beneficial!) flies. A team of researchers at UMass Amherst, led by Joe Elkinton, is set to release 1,000 parasitic flies (Cyzenis albicans) in Wellesley in an effort to combat the winter moth caterpillars (Operophtera brumata) currently defoliating deciduous trees across the eastern part of the state. Read more in this story from The Boston Globe.

Update 5/12/08:WBZ Radio 1030 put up this YouTube video report by Carl Stevens, showing the actual release.

Winter Moth Biocontrol

Last week I headed out to UMass Amherst to meet with some of the people in Cooperative Extension that participate in the Massachusetts Introduced Pests Outreach Project. While there, I got a tour of the Elkinton Lab, where they are working on a few different biological control projects that target insect pests. One of those projects is the rearing of a parasitic fly, Cyzenis albicans, for control of the winter moth (Operophtera brumata).

Right now, winter moth eggs are just about ready to hatch in Massachusetts, but in the Elkinton lab, the caterpillars are several weeks ahead of schedule, being raised in the best of conditions for the sole purpose of becoming incubators for the biocontrol flies.

Here is a batch of fly pupae:


The pupae are placed in a cage along winter moth caterpillars and some tree branches. Once the flies emerge, the presence of the caterpillars causes them to lay eggs. The eggs are collected and then fed to other caterpillars, to raise even more flies that will be released into the wild later this season.

Links:

• MIPOP Winter Moth Fact Sheet
  
• Biological Control of Winter Moth in Massachusetts (2005 Project Report, pdf file)
  
• Winter moth update, UMass Extension Landscape Message for April 17, 2008