Gypsy Moth Caterpillars
We encourage every homeowner in the Lake Beulah area to take action now. Please take a walk around your property and look for the Spongy Moth egg masses and caterpillars, which will be emerging now. The caterpillars and egg masses are easy to identify (see photos). The caterpillars are voracious eaters. They will dine on the leaves of aspen, birch, crabapple, hawthorn, linden, mountain ash, oak, willow, dogwood, green and white ash, honey locust, silver and red maple, tulip tree. Blue spruce and white pine can occasionally be attacked.
How to identify the egg masses, caterpillars and moths
Egg masses are beige with a velvety texture and spongy consistency. Egg masses can be attached to a variety of surfaces and can be well hidden. They and are often found on buildings, lawn furniture, mail boxes, rocks and trees. The caterpillars have a “hairy” appearance and are initially a mottled grey color. They soon develop pairs of blue and red bumps running down their backside. Mature caterpillars reach lengths of 2+ inches. Adult moths are approximately 1-1.5 inches long. Female moths are slightly larger than males and are a pale color. Females cannot fly, but do release a chemical pheromone to attract males. The males are a dark brown color and fly to females to mate.
What can you do to remove the egg masses, caterpillars, and moths—
1. Egg masses can be scraped off surfaces with a putty knife and dropped into a container of soapy water for several days or bagged and discarded to kill them. Alternatively, egg masses can be treated with a dormant horticultural oil.
2. Sticky Bands: Sticky bands can be used around tree trunks to capture and kill small caterpillars. The UW-Madison Division of Extension Spongy Moth website has full instructions for this method: https://fyi.extension.wisc.edu/spongymothinwisconsin/
3. Burlap Bands: Since larger caterpillars hide during the day, a band or skirt of burlap hung around the trunk of a tree with twine can offer a hiding spot. Burlap bands must be checked daily, and caterpillars can be knocked into a container of soapy water to kill them.
4. Insecticide Sprays: For trees and shrubs that are short enough in height, insecticide sprays can be an option. Organic and reduced-impact sprays include insecticidal soaps, horticultural oils, pyrethrins, spinosad, and Bacillus thuringiensis kurstaki. Trees close to the lake cannot be sprayed, however there is an injectable insecticide that is effective.
5. Hire an arborist to check and treat your trees.
For more information visit: https://spongymoth.wi.gov/Pages/home.aspx
The information included above is from the University of Wisconsin Extension program (https://hort.extension.wisc.edu/files/2022/04/Spongy_Moth_2022.pdf)