Control With Burlap Barriers

Sometime in June or early July, gypsy moth caterpillars become night feeders and come down from the tree each morning, precisely at dawn. Then they go back up the trunk precisely at dusk, just like clockwork. You can take advantage of this behavior and trap them on their way back up the tree in morning.

For large trees, wrap a piece of natural burlap a foot wide around the tree trunk, about chest-high. For smaller trees the band should be no wider than half the diameter of the tree. Wrap the band around the tree, and tie the burlap strip at its center with heavy twine, letting the top fold over about half way to form a fold or skirt. Descending caterpillars will hide under the fold. In the late afternoon, put on garden gloves [631 300] and sweep the caterpillars off the burlap into a container of detergent and water. For this technique to work effectively, you need to be prepared to deal with caterpillar disposal every day for several weeks. Burlap barriers can help reduce defoliation in light to moderate infestations.

Control With Sticky Barriers

Bands of sticky materials mounted around tree trunks also stop gypsy moth caterpillars as they make their way up and down tree trunks each day. You can buy commercial sticky bands to wrap around the trunk or your tree.

A do-it-yourself version involves wrapping a 4-inch-wide piece of cotton batting or similar material around the trunk of the tree, about chest high. Over this, tie a 6- to 12-inch-wide piece of tar paper smeared with an adhesive pest product such as Tanglefoot. Replace the band whenever needed until mid-July, at which time you should remove it. Sticky barriers can help reduce defoliation in light to moderate infestations.

Note: The U.S. Department of Agriculture cautions against applying any sticky substances, especially grease, tar, or other petroleum products, directly to the bark of trees; this can cause swelling and cankering.

Help Stressed Trees And Shrubs Recover

If you can reach the top of the tree or shrub with a backpack sprayer fitted with an extended wand, then you can spray the foliage and drench the roots with what is called a “bioactivator” or seaweed- or kelp-based plant tonic. This product contains seaweed extracts, hormones, enzymes, and other growth-enhancing substances. Feed the tree or shrub according to label instructions. Applying a tonic once a month until the end of the growing season is good therapy for a tree or shrub devastated by a massive gypsy moth attack.

Defoliated trees and shrubs may suffer further from lack of water. As soon as major defoliation occurs, keep the soil around the roots moist but not waterlogged. Water the soil 1 1/2 times the radius of the drip line very thoroughly every week, less if rainfall is sufficient. Also be sure to soak the soil thoroughly before the ground freezes in the winter. Put down a 4-inch-thick layer of mulch around the tree to buffer the ups and downs of temperature in the soil that can damage stressed roots.

Click here for more information on Using Mulch.

Destroy Egg Masses

In late April or May, search your yard for the characteristic fuzzy tan-colored egg masses. Scrape them off trees and other vertical surfaces with a putty knife or other flat instrument. Search the ground at the base of trees, too. Dump egg masses into a container of kerosene or paint the egg masses in place with creosote, or simply put on a pair of work gloves and smash them on the spot.