Orangestriped oakworm (left) may feed in large groups (right).
Cooler temperatures are upon us and soon we will be donning the colors of fall. The orangestriped oakworm, which is a black or brown caterpillar with orange or yellow stripes, is perfectly outfitted for its late summer and early fall debut.
The orangestriped oakworm is a native moth caterpillar that feeds on the foliage of hardwood trees this time of the year. Along with their festive coloration, they have two prominent horns near their head and small spines covering their body.
As their name suggests, they primarily feed on the leaves of oak trees but may also attack maple, hickory, cherry and hazelnut. When they are done feeding, larvae will drop from trees and wander around in search of a site to pupate. When this occurs, they may be found crawling on sidewalks, driveways or parking lots.
The good news is that because these insects feed on tree leaves late in the growing season, trees that are fed upon are often unphased and will re-leaf the following spring. The biggest concern is the aesthetic impact to yard trees.
Because tree health is typically not impacted, control is usually not recommended. Moreover, birds, diseases and parasites may help to naturally lower the population next year. In some cases, pesticides can be used, but they are only effective when caterpillars are very small. By the time the caterpillars and damage are noticed, it is usually too late for chemical control. If you wish to address concerns about appearance, your best bet may be to hand-pick or shake the larvae from small trees.
Orangestriped oakworms defoliate hardwood trees (mostly oaks) in the late summer and fall.