Gypsy Moths are Hatching

Redbuds are in bloom and oak trees are leafing out, so that means that gypsy moth egg masses are starting to hatch.

The previous two years saw cool, wet Springs in the Middle Atlantic States which promoted the spread of a fungal disease, Entomophaga maimaiga, of the gypsy moth caterpillar. That disease, coupled with management measures, and their natural Boom-Bust multi-year life cycle greatly reduced their numbers to the point where Pennsylvania’s Department of Conservation and Natural Resources (DCNR) will not have to spray for them this Spring. That doesn’t mean we should relax our vigilance to keep these destructive pests at bay. In 2007 we experienced the outbreak phase with extremely high caterpillar numbers,

severe defoliation

and tree loss,

as you can see from these pictures taken that year in Quincy Township.  In 2008, surveys gave some hope that the population was declining, but as this picture from Adams county can attest, there were still significant outbreaks.

Unlike other states that participate in the U.S. Department of Agriculture Forest Service's  program to suppress Gypsy Moths, Pennsylvania requires that a request from the landowner be submitted before evaluation to conduct a spray operation can even take place.

Monitoring in 2010 will give some warning of the next outbreak phase, but landowners frequently don’t request treatment until caterpillars are noticeable and it is too late to spray that year.

Because of program deadlines and the moth life cycle, it takes a year to get program approval. Since the selective, organic compound bacillus thuringiensis (BT) that is used in DCNR’s program must be eaten by the caterpillar during its early growth stages, spraying at the right time is also crucial. This is why the program often seems more reactive than proactive.

So, during the next few weeks, carefully check your oak trees to look for the caterpillars. If you think you see them, or if you experienced an outbreak in years’ past, and want to be considered for potential spray operations next year, please contact the Penn State Cooperative Extension Office at 263-9226, if you live in Franklin County, or the local coordinator in your county.

For more information go to DCNR’s gypsy moth site, and click on the link to the Gypsy Moth Suppression Program.

My counterpart in York County, Diane Oleson, wrote a great article for Penn State's Forest Leaves quarterly newsletter, where much of the information for this post was derived.