Dealing with Gypsy Moths
Using Barrier Bands
Mid-spring (around late April) is the time to apply sticky barrier bands around trees, about 2-4 feet above the ground. Right after hatching, caterpillars disperse to neighboring trees on silk threads, but many will fall out of the trees. Barrier bands will prevent caterpillars from returning to the trees and help reduce damage from feeding.
- Dark, hairy gypsy moth caterpillars hatch in the spring. They are easily identified by five pairs of blue dots followed by six pairs of red dots lining their backs.
- Young caterpillars feed primarily during the day, while older caterpillars feed at night.
- Young caterpillars spread to new locations by crawling to the tops of trees, where they spin a silken thread and are caught on wind currents.
- Full-size caterpillars are 1 1/2 - 2 inches long.
- Gypsy moth caterpillars do not produce a web, distinguishing them from web-making caterpillars such as the eastern tent caterpillar and the fall webworm.
Why Gypsy Moths are Harmful
- The caterpillar stage causes all the damage. After hatching, the caterpillars may feed for up to two months on the leaves of trees.
- As the caterpillars mature, they expand their diet (and their big appetite) and will ultimately feed on around 500 species of trees and shrubs.
- The leaves of most oak species are their preferred food source, and populations won't build up in areas that don't have a reasonable oak tree population.
- Heavy defoliation causes stress to the infested trees, making them susceptible to secondary attacks by other insects and pathogens, which can lead to plant death.
- They can multiply to destructive levels in just one to two years.