Winter Moth (Operophtera brumata)

These destructive, leaf-eating caterpillars feed on the swollen buds of many woody ornamental plants in early spring and are extremely prevalent in Eastern Massachusetts. The young caterpillars migrate from bud to bud, crawling inside and devour them from within. If they are not treated for in the spring, older caterpillars feed on expanding leaf clusters and are capable of defoliating entire trees.

Many deciduous plants are susceptible, including oaks, maples, Japanese maples, cherries, apples, crabapples, and blueberries. The caterpillars may also drop down and begin feeding on plants like roses and herbaceous perennials that are located beneath or near infested trees.

Identification

During the Early spring months (March and April) Winter Moth caterpillars look like inchworms and can be seen feeding on the emerging leaves of host plants as the leaf buds are opening. To minimize damage however, it's best to treat for them before the leaves begin to emerge.

Treatment

The Winter Moth is a pest that is particularly difficult to treat for because you need to spray most products on the tree to be effective. To effectively treat for the Winter Moth in the early spring trees should be sprayed with products that will be ingested by the the caterpillars as they feed.

Thurgicide (B.t. kurstaki)

This is a great organic way to treat the insect provided you catch them early enough in the season. When foliage is still emerging it is necessary to reapply often due to the need of the B.t. to be ingested.

Monterey Garden Insect Spray (Spinosad)

This is part of a new group of pesticides that is known as Bio-rationals that are safer for the environment and have less toxicity to beneficial insects.