09/02/24 - 146 New Stories - REAL Environmental & Conservation Leadership In PA: http://tinyurl.com/yck6vkb4
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Gypsy Moth Numbers Expected To Remain Low This Year
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It’s that time of year again. In the month of May, the gypsy moth (Limantria dispar) eggs hatch. This hatch timing depends upon the temperatures for late April and early May. Given the temperatures that we have been experiencing in Pennsylvania during that time, the gypsy moth eggs will be a little late in hatching.
There are many spring defoliators and gypsy moth is only one of them. The reason the gypsy moth has been such a problem historically is that it is not a native insect. It is an invasive, alien insect species that originated from Europe. It was brought from Europe to Massachusetts in 1869 by an amateur entomologist from France who was going to try to breed the European gypsy moth with the Asian silk moth.
The gypsy moths wouldn’t interbreed with Asian silk moths and someone left the cage door open at one point, releasing the gypsy moths into the environment.
With no natural enemies to slow it down, the gypsy moth’s population exploded across the landscape. They are particularly fond of oak leaves, and have killed hundreds of thousands of acres of oak trees in the past 142 years.
That being said, the 2011 outlook for Pennsylvania in terms of gypsy moth, from our perspective, is good. The Bureau of Forestry’s Division of Forest Pest Management spent a great deal of time surveying for gypsy moth egg masses throughout Pennsylvania. Crews sampled 1,048 plots throughout the state. Of those 1,048 plots, only 29 were recorded as having egg masses. Of those 29 plots, 18 of them had just one egg mass and only 11 had more than one egg mass.
It was only four years ago, during the gypsy moth infestation of 2007 and 2008, that there were many plots recorded with greater that 20,000 egg masses per acre.
The reason for the recent collapse of the infestation of 2007/2008 is a fungal pathogen of gypsy moth—Entomophaga maimaiga (Em). This fungal disease of gypsy moths was first introduced in 1910. It exists as spores in the soil duff, and is particularly virulent when there is a cool wet spring, something that we experienced in 1989 and 1990 and each spring since 2008.
This fungus is hoped to spread out gypsy moth outbreaks to 10 to 15 years. A large healthy gypsy moth egg mass can contain 750 to 1,000 eggs. With this potential population increase, it is easy to see how gypsy moth can explode very quickly given good conditions.
Still, there will not be any broad-scale infestation of gypsy moth across large areas of Pennsylvania in 2011.
This fact doesn’t mean that Pennsylvania residents shouldn’t be observant. Residents should report local gypsy moth infestations to their Bureau of Forestry’s regional forest health specialist or county officials.
In future articles, we will review how to differentiate among the gypsy moth, Eastern tent caterpillar and forest tent caterpillar. These three insects are very often confused with each other.
For more information, visit DCNR's Gypsy Moth webpage.
(By David A. Schmit, forest health specialist for DCNR's Bureau of Forestry. Reprinted from the May 25 DCNR Resource newsletter)
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5/30/2011 |
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