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
  

Biocontrol released in Michigan for emerald ash borer

Researchers from the USDA have added another tool to the arsenal against the emerald ash borer (Agrilus planipennis, "EAB"). As reported in this article from E: The Environmental Magazine, three different wasp predators, all natural enemies of the EAB, are currently being reared and released into the wild to fight the tiny green invasive beetle. The release sites are all in Michigan, where ash trees have been under attack since the late 1990s.

The emerald ash borer has never been found in New England, but state agencies in Massachusetts remain on the lookout for this pest. To learn more about it, check out our EAB pest fact sheet. You can learn more about this and other pests of the Great Lakes region by visiting the Illinois CAPS blog.

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.

Biocontrol Successes

There is a good article in the Boston Globe today summarizing the state's work on the Purple Loosestrife Biocontrol Project. Purple loosestrife (Lythrum salicaria) is one of the 141 plant species on the state's Prohibited Plant List, and was categorized as invasive by the Massachusetts Invasive Plant Advisory Group.

Beth Suedmeyer of the Massachusetts Wetlands Restoration Program currently heads the biocontrol project, which has released over 300,000 Galerucella beetles to eat purple loosestrife since 2000. As with most biological controls, a Galerucella beetle attack does not immediately destroy purple loosestrife, rather, the beetles are a tool used to keep current populations of this invasive plant in check.

Suedmeyer is now training citizen scientists to raise and release the beetles, which have shown some evidence of beginning to breed and spread on their own. Visit the Purple Loosestrife Biocontrol Project for more information, including how you can raise beetles and what to do if you see a Galerucella beetle in the wild.

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