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Connecticut Facing Another Tough Year With Gypsy Moths

Wikimedia Commons
Gypsy moths are one of the most destructive pests of hardwood trees in the eastern United States. Gypsy moth caterpillars eat the leaves of more than 500 species of plants.

Gypsy moths have been with Nutmeggers for a while. The pest was first detected in Stonington in 1905, and by the mid-20th century, spread statewide. The pests hurt trees, annoy homeowners, and in recent years -- have been growing in number. 

A 1981 outbreak was particularly damaging, with caterpillars munching on about 1.5 million acres of forest.

"Essentially, the entire state was defoliated," said Christopher Martin, director of forestry at the Connecticut Department of Energy and Environmental Protection.

Martin said nothing that dramatic is expected this year, but lately, gypsy moth numbers have been trending up, catalyzed by the state's two recent dry springs.

According to the Connecticut Agricultural Experiment Station, gypsy moth caterpillars hit 175,000 acres in 2015 and over 200,000 last year. While that was only a slight increase in acerage, 2016 defoliation was much more severe.

"There [are] varying degrees of defoliation. We even see that in the current outbreak," Martin said. "You could lose 30 percent, 50 percent of the canopy to gypsy moth caterpillar feeding. Then in other areas, with very high concentrations, 100 percent."

"Even defoliation of what typically are non-host trees," Martin said. "Needle trees like pine and hemlock. The gypsy moth caterpillar will eat those before they starve themselves out."

Credit Office of the State Entomologist / CAES, Kirby Stafford
This aerial survey map shows, in red, areas defoliated by the gypsy moth in 2016. Overlaid in green are results of a recent egg mass survey conducted by state entomologists.

Martin said entomologists go out and look at eggs in the field to project outbreaks and recent surveys (see above) point to another tough year in 2017.

But gypsy moth populations tend to go in cycles, which means there is hope, he said, as long as it keeps raining in May and June. 

"There's a naturally-occurring fungus in the soil that is specific to attacking gypsy moths," he said. "The soil moisture content needs to be high enough to activate the fungus in order for it to attack." 

There are currently no plans for state-funded aerial spraying. But gypsy moths can still be a big problem. So what can landowners do to protect trees like oak and aspen, which the U.S. Forest Service said gypsy moths can target?

Martin said give the trees a check-up -- if they're healthy, they can usually survive one -- or even two or three -- defoliations from gypsy moths. If you're still concerned, Martin said contact a licensed arborist, who can help you work out a spraying plan.

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