RI Gypsy Moth Caterpillar Population Expected To Rise This Spring For Third Consecutive Year

May 8, 2017

Rhode Island is expected to see an increase in the gypsy moth caterpillar population this spring for the third year in a row, according to a report by the state Department of Environmental Management. 


Last fall as a part of its annual survey, the DEM counted the number of gypsy moth egg masses throughout 142 designated forested areas. The DEM found more than 36,000 egg masses, compared to 3,523 in 2015 and 44 in 2014. 

"Based on last fall's survey counts, we anticipate that there will be hundreds of millions of caterpillars hatching throughout the state this spring," Paul Ricard, forest health program coordinator for DEM's Division of Forest Environment, said. 

The caterpillars feed on foliage, which drains trees of energy and can cause them to die. Last year, the caterpillars defoliated nearly 226,000 acres of forestland. 

Ricard said he’s not recommending the use of pesticides to control the caterpillars' population because only a fungus that kills the caterpillars before they reach adulthood can eradicate them. The fungus hasn't been able to thrive because the last three springs have been very dry, Ricard said.

The pesticide also pose a risk to other insects. 

"There are certain bees and butterflies that are killed by (the pesticide)," Ricard said.  "So if you want to use it on house lots or small areas,...that risk is really minimal, but once you start applying it on a landscape scale, that risk increases."

As of now, the state does not plan on spraying pesticides to control the caterpillar population. 

State House Minority Leader Patricia Morgan delivered a letter to Gov. Gina Raimondo last week asking her to address gypsy moths by commencing a statewide caterpillar eradication program.