While the butterflies and moths that develop from caterpillars are rarely destructive, the caterpillars eat large amounts of plant materials and can do significant damage to trees and other plants. Like many other hardwood trees, oak trees are commonly infested by caterpillars. The various types of caterpillars feeding oaks are numerous and diverse with a number of different characteristics.
A type of caterpillar that develops into a moth, cankerworms have long, cylindrical bodies and capsule-shaped heads. One of several types of caterpillars commonly called inch worms, these caterpillars have several pairs of legs in the front and several in the back. They are often dull or dark colours. They are the most active in November and December. It is during this time that they begin feeding on your oak tree and lay eggs nestled on leaves between branches or near shrubs.
Forest Tent Caterpillar
The forest tent caterpillar is common throughout both the United States and Canada and is seen on many hardwood trees. These caterpillars are seen in outbreaks occurring usually once a decade. They are common near the ponds of the Southern United States. They can strip the leaves of large expanses of trees, and can cause the complete defoliation if present in very large numbers. The caterpillars can feed on oaks for as long as five or six weeks after hatching.
The greenstriped mapleworm is one of the many "worm" varieties of caterpillar that infest all types of oak trees. They defoliate the trees if their population is large enough. They are found throughout the Eastern United States and also feed on maples. These caterpillars are green with white stripes and grow to become one of the largest species of caterpillar. They lay eggs that hatch in 10 days, and these eggs can be seen as large clumps of on the underside of oak tree leaves.
Other Caterpillars and Treatment
Other caterpillars that feed on oak trees include the yellownecked caterpillar, the stinging caterpillar, the spiny oakworm, the redhumped oakworm and the pinkstriped oakworm. While a single attack from one variety of these caterpillars will not kill your tree or shrub, they present problems. Control these caterpillars and their eggs by using any of a number of caterpillar-specific insecticides.