Conservation Focus

Gypsy Moth Outbreak

gypsy-moth-larva22016 was a particularly bad year for Massachusetts, Rhode Island and Connecticut when it came to gypsy moths. For the first time in 35 years there was wide spread and severe tree defoliation by gypsy moths. The outbreak was linked to the recent and severe statewide drought.

The gypsy moth is a native of Europe and it’s history in North America is unusual to many other exotic species because we know exactly where and when it was introduced.

Etienne Leopold Trouvelot of Medford , MA was trying to hybridize the gypsy moth with native silk moths from France. The gypsy moths escaped from his home in 1869 and in the 1880’s we saw the first tree defoliation in Medford.

So what took place in 2016 to create the gypsy moth population? The answer is drought. Rainfall from May 1 to June 20 is required for a particular fungus which kills gypsy moth larvae to germinate and penetrate the caterpillar. In 2016 drought conditions prevented this from happening in southern New England. Some moth larvae was killed this year but not in the proportions as other years and not enough significantly reduce the population. We need to hope that May showers will come back to help in 2017.

Come spring, be on the look out for gypsy moth caterpillars.

Spring has arrived and so have the moths.  Perhaps the wet spring will help with next years population.