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WHAT TO DO ABOUT GYPSY MOTHS IN YOUR BACKYARD

Gypsy moths in your backyard can be a real nuisance. At high populations, the caterpillars seem to be everywhere. Their feeding stresses and may kill valuable trees. You won't get rid of every gypsy moth in your yard, but you can take some simple steps to cut their numbers.

First, you need to know that you will find gypsy moths in four different life stages, and they all look completely different:

Kinds of gypsy moths

Caterpillars (larvae) hatch in early to mid-May and feed through June.
Pupae are similar to cocoons and are present from late June to late July.
Adult moths emerge from pupae in mid July to late July and may be seen until late August.
Egg masses are laid in late July and August and will not hatch until the following May.

Here's what you can do at each life stage:

Sticky bands catch caterpillars as they head up into trees to feed after they hatch, or if they've fallen out of the tree.

When: Early May-late July

How:

  1. On dry bark, at about chest height, wrap duct tape around the tree. Put the sticky side against the bark. Make the strip about 5 inches wide, and tuck the tape into the folds in the bark.
  2. 2. Smear Tanglefoot (available at garden centers) on the tape.
  3. 3. Check bands regularly to be sure they are not clogged with insects or dirt. Apply more Tanglefoot or replace bands as needed.

Burlap bands catch older, larger caterpillars. These caterpillars crawl down the tree trunk during the day to hide from predators and climb back up as evening approaches.

When: Early June to late July

How:

  1. Cut a strip of burlap 12-18 inches wide and long enough to go around the tree.
  2. Wrap the burlap around the tree at chest height, or just above the sticky band if there is one in place. Tie a string around the burlap 6 inches from the top edge. Let the top 6 inches flop over and form a two-tiered skirt.
  3. Check the bands every day from mid-afternoon to about 6:00 p.m. Wear gloves or use a tweezers to collect caterpillars, because the hairs on them can cause a rash. You might also find and collect pupae, adult moths or egg masses.
  4. Drop them all in soapy water (dishwasher detergent works well).
  5. Once the caterpillars and adults are dead, drain the water and throw the insects in the trash.

Egg masses contain about 600 eggs each. Left undisturbed, they will hatch into caterpillars in the spring. Egg masses are roughly tear-drop shaped, 1 inch to 1 1/2 inch long. They are yellowish tan, and look like felt.

When: Late July to early May. It's best to wait until after a hard frost to allow parasites to build up. These parasites may kill egg masses that you can't reach. Also, it is easier to see the egg masses after the leaves have fallen.

How:

  1. Use a tool such as a putty knife that can reach into cracks or clean flat surfaces.
  2. Look for egg masses on the bark of trees, at all levels, and under loose bark. Also check under porches and decks, on wood piles, under tarps, on outdoor furniture and equipment, behind signs or any thing else nailed to trees, and even on rocks.
  • Carefully scrape the egg masses into a Ziplock bag. You might find it helpful to squirt water on them first to prevent crumbling and blowing away.
  • Seal the bag and microwave it for 1 minute. Instead of microwaving, you can also cover the eggs with a 50/50 mixture of corn or soybean oil and water.
  • Throw the egg masses in the trash.

* Avoid handling the egg masses, because the hairs covering them may cause a rash.

Pesticides are effective only against gypsy moth caterpillars - no other life stage. If you decide to treat with pesticides, remember:

  1. If you apply the pesticide yourself, read the label to be sure it is effective against gypsy moth caterpillars, and FOLLOW LABEL DIRECTIONS exactly.
  2. Insecticidal soap is readily available at garden centers and is effective against gypsy moth caterpillars. You must collect the caterpillars and drop them in a water/soap mixture.
  3. If you hire someone to do the treatments, be sure to hire a certified, licensed, reputable applicator. Do not hire an applicator to treat any life stage other than caterpillars.
  4. Don't treat if you don't see caterpillars. There is no preventive treatment to keep caterpillars from coming to your trees.

Keeping trees and shrubs healthy is the first line of defense against gypsy moths. The second line of defense is making your yard less pleasant for gypsy moths. While the caterpillars will eat the leaves of hundreds of species, they do have some favorites and some that they avoid. Keep this in mind when choosing new plantings for your yard.

  1. Caterpillars prefer oak, crab apple and apple, willow, aspen, birch, basswood, linden, and tamarack.
  2. Caterpillars avoid ash, cedar, locust, balsam fir, pine, maple, nut trees, beech, spruce and hemlock.

Color photos may help you identify the different life stages of gypsy moths. You can check the Website or call toll-free at 1-800-642-MOTH to request color brochures be mailed to you.

Remember, it is NOT a gypsy moth if it is:

  1. A caterpillar earlier than May or later than mid-July.
  2. An adult moth earlier than July or later than August.
  3. A white moth that flies. (Female gypsy moths are white, but they cannot fly. Male gypsy moths are brown.)
  4. Building a web or "tent" in trees.

Don't move gypsy moths! 20 counties in eastern Wisconsin are under quarantine, meaning that it is illegal to carry items out of the area if they harbor gypsy moths. We can't inspect every moving van or camper, so we're depending on you to check over the wood or lawn furniture you take to your cottage up north, the RV you drive south for the winter, or anything else that might carry egg masses, pupae or caterpillars. Be a good neighbor - inspect.

Wisconsin Cooperative Gypsy Moth Program
A joint effort of:
Wisconsin Department of Agriculture
Trade and Consumer Protection
Wisconsin Department of Natural Resources
U. S. Forest Service
U. S. Animal and Plant Health Inspection Service
University of Wisconsin