Gypsy moth feces fell like rain last year – what can be done?

A gypsy moth caterpillar. They’ve barely been an issue for three decades, but now, after one too many dry seasons, a fungus hasn’t been able to proliferate enough to keep the caterpillars at bay.

By Max Dodson, Community News Service

This past summer the Gypsy moth population exploded in the state. There were so many caterpillars, people compared the sound of their feces falling off trees as “rain.” Sometimes sidewalks and pathways were covered in the larvae and there seemed to be Gypsy Moth Caterpillars everywhere.

The problem became so severe that in their meeting on Tuesday, August 10th, the Essex Conservation and Trails Committee discussed a need to study the problem and find ways to eliminate the pests. However, town officials say they need help from state environmental authorities to conduct a worthwhile study.

”There was a suggestion of doing a survey, but it hasn’t gone farther than that, since it’s far beyond the capacity of the town of Essex to address,” said Darren Schibler, staff representative for the Essex committee.

The study mentioned above would include a look at the areas of defoliated trees impacted by the gypsy moth, as well as a survey of the egg masses on the trees themselves, much like this one completed in the Northeastern US in 1997.

The Vermont Department of Forests, Parks and recreation is closely watching the moth population by “monitoring egg masses this fall and formulating recommendations for next year based on findings,” said Tapper. Should an outbreak occur next summer, officials are prepared to intervene and stop the spread of the Gypsy Moth, Tapper said.

An example of just how devastating the Pests can be to forests is the defoliation that occurred on Arrowhead Mountain this past summer. Comparing the forests on the mountain before and after the Gypsy Moths feasted is night and day. 

The 1991 Gypsy Moth outbreak was the last major infestation, according to a state Department of Forests, Parks and Recreation post, when foliage across the state was devastated. 

What stopped the 1991 outbreak was a Japanese fungus that targets only Gypsy Moth caterpillars, which a Cornell University researcher called “perhaps one of the most successful fungal biological control agents.” The fungus that year was helped by heavy rain. But this natural solution may not be as effective as it was — dry weather in recent years has hampered growth, according to The Associated Press.   

Without strong conditions for this fungus to grow, future outbreaks of Gypsy Moths could be larger, harder to stop, and more difficult to contain. 

There are smaller solutions though. Ethan Tapper, a state forester in Chittenden County, said people can work to protect the trees on their own property using a low-impact pesticide made up of a bacteria that arborists can easily apply. 

“This strain of bacteria is specific to moth larvae, and its toxic properties get activated when it interacts with the caterpillar’s digestive tract,” Tapper said via email. Essentially, it’s harmless to everything but the moths themselves. 

The recent outbreak is exacerbated by dry conditions, Tapper said. 

“The reason for the present outbreak is thought to be draughty conditions over the past few years, which are suppressing the population of the fungus,”  Tapper said.

Categories: Environment

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