A Closer Look At The Browntail Moth Timeline

As with most insects, the browntail moth life cycle occurs in four parts: egg, larval, pupal and adult. Fortunately for those in the Northeast, the browntail moths are only toxic for a portion of their life cycle. Browntail moth eggs are laid in late summer, and the larvae emerge in late August and early September to begin building their winter webs. The most dangerous time for people during the life cycle is between April and August, when the caterpillars are out feeding before they enter the pupal stage and emerge as adult moths to lay their eggs. 

After spending the winter in their nests, the caterpillars emerge to begin feasting on the new spring foliage. Browntail moth caterpillars reach full growth, about 1.5 inches long, in mid to late June. At this time, they return to weave their cocoons for pupation. These cocoons contain large concentrations of the browntail moth caterpillars' toxic hairs that are easily spread through the air. 

Once the browntail moths develop and emerge from their cocoons in July, they begin to prepare to lay their eggs. Each female will lay between 200 and 400 eggs. The moths are no longer toxic, but it is not long before the toxic caterpillars emerge again. 

The cool, damp environment is perfect for several funguses and viruses that kill the caterpillars. The fungus entomophaga aulicae is extremely dangerous to the caterpillars and has an extremely high mortality rate. However, we are still seeing elevated rates of browntail moths on the Maine coast, and further inland areas. 

Citizens need to remain vigilant and try to remove nests whenever possible. If you are exposed and develop a rash, try Browntail Moth Rash Relief spray as an all-natural remedy. Our Maine-made relief spray is available at many retailers throughout the Downeast. Visit the “Stockist” page on our website to find a retailer near you!