Gypsy Moth Program

Gypsy Moth Outlook 2019/2020

Every June, the PA DCNR gives annual regional briefings on the state's gypsy moth situation. The Centre County Assistant Director of Planning and the GM Coordinator attended the 2019 briefing to assess the likelihood of future outbreaks in our county in 2019/2020 and onwards.

The DCNR Bureau of Forestry specialists were unanimous in their opinion that there will be no gypsy moth activity in Centre County in 2019/2020. Moreover, because there are minimal gypsy moth populations in adjacent counties, it is very likely that we will be clear of gypsy moths in 2020 as well.

Are We Now Fully Protected from Gypsy Moths in Centre County?

Short answer: No. A series of two or three dry springs could tamp down the activity of pathogenic fungus and allow the low background gypsy moth population (which is always present in low numbers) to expand exponentially, increasing its numbers a hundredfold each season until it becomes a major outbreak.

What Do I Do If I See A Gypsy Moth?

First, positively identify the caterpillar as a gypsy moth – google 'gypsy moth' for pictures. If the caterpillars are forming webs on the tips of branches, they are definitely not gypsy moths!

Gypsy moths are always present in Centre County at low levels, so you should expect to see the odd caterpillar. However, if you see many GM caterpillars and especially if you see that they are defoliating foliage, please report this to the contact name at the top of this page who will pass on the information to the county's volunteer GM coordinator.

Health Facts: Control Agent

Only one gypsy moth control agent is used in the state suppression program, a biological insecticide called B.t. or B.t.k.. B.t. is an abbreviation for Bacillus thuringiensis var kurstaki which is a soil bacterium which produces a protein which binds to specific receptors found only in the guts of Lepidoptera (butterflies and moths) and eventually ruptures the gut walls, causing septicemia and death.

The Pennsylvania Department of Conservation and Natural Resources (DCNR) states that "B.t. has the highest known degree of safety to human health and the environment of any insecticide currently on the Market." The US Department of Agriculture (USDA) has published extensive information on B.t. in their Gypsy Moth Environmental Impact Statement (EIS) which is available in a book (but not in PDF) format from the USDA. The USDA concluded that based on "both the available epidemiological studies as well as a long history of use, no hazard has been identified for members of the general public exposed to B.t.k. formulations".

The USDA ranks relative risks to the public in all their activities by an index called the Hazard Quotient (HQ). The HQ is measured on a logarithmic scale, from 0.0001 to 10,000. A value greater than 1 means an effect may be observed after exposure. B.t. is given a value of 1 (2 in cases of extreme exposure). By contrast, an infestation of gypsy moth is given an HQ of 100, with an extreme exposure being given an HQ of 7,000. This is a result of skin lesions, respiratory tract effects as well as the psychological stress associated with living with large numbers of caterpillars in a homeowner's vicinity. 

Gypsy Moth Links