Trees attacked by gypsy moth, usually oaks, can be very large when mature. Don't try to treat the gypsy moth yourself if you have a large tree. Larger trees should be treated by a professional arborist who will have the proper equipment and expertise. For example, a 30-foot tree will require about 10 to 20 gallons of spray material for effective control. This is best done by a trained applicator.
What Not To Do If Tree Is Defoliated
If the tree has been defoliated then there should be no crown thinning by arborists or fertilizing by anyone for at least two years after the last defoliation. Both these practices were common among tree professionals but have since been shown to be very harmful and stressful to the tree under attack.
For Smaller Trees There Are Some Non-chemical Techniques
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.
Control With Slippery Barrier Tape
They steadily enlarge in size and by mid-July they are well fed and ready to pupate. By this time the caterpillars start to move up and down the trees; they climb down to hide during the day and climb back up at night to feed. When you put up the slippery tape they can't get back up the tree. Real sneaky.
Trednot Slippery Caterpillar Barrier Tape 30 ft Roll
- Protects trees from caterpillars and other crawling insects
- Non-Chemical 2" x 30 ft roll protects 25 four-inch trees
- Applied to the trunk of the tree as a slippery barrier
- The barrier is too slippery for caterpillars to climb across it.
- Stops defoliation from migrating caterpillars
Slippery Caterpillar Tape is a 30 ft roll of tape that is an adhesive on one side, to attach to the tree trunk, and slippery on the other side to prevent upward caterpillar migration. No Chemicals involved. Does not kill the caterpillars...they just go elsewhere. Used by homeowners to protect residential trees. Also used by fruit tree nurseries. To watch a video of the tape being used...past this in your address bar... www.you tube.com/watch?v=wq8oqPxLS8M (remove the space between you and tube
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.
Organic Insecticide For Gypsy Moths
The decision to use insecticide to control gypsy moths depends on the condition of the trees or shrubs you want to protect. If they are healthy and vigorous they may not need spraying. If, however, they do need to be sprayed, you can treat small trees and shrubs with a backpack_sprayer. For small trees and shrubs up to 15 feet tall you will need a trombone sprayer.
So when you can see caterpillars, spray tree or shrub leaves thoroughly with a product containing Spinosad when the worms are actively feeding which will be early in the season. This will likely be sometime between May 1 to June 1, depending where you live. The gypsy moth caterpillars eat the Spinosad which is a bacteria that affects their digestion, when they chew on the leaves of the tree. They stop eating soon and die within a few days. Spray the entire area where the caterpillars are feeding as directed on the product label. We say again, in situations where the tree or shrub is very tall and difficult to reach, hire a professional arborist in the early spring to spray them properly and safely.
AzaMax will control gypsy moth caterpillars
AzaMax is a natural product with a broad spectrum of pest control and broad plant applications. AzaMax is an anti-feedant and insect growth regulator which control (kills) pests through starvation and growth disruption within two or three days. Therefore this product is used when the bugger is chomping on the foliage. Any of the sprayers can be used to apply AzaMax
For more information about AzaMax go to the Yardener's Tool Shed; click here
Bonide 252 16 oz Captain Jacks Dead Bug Brew Concentrate
- Contains Spinosad, a naturally occurring soil dwelling bacterium.
- Kills gypsy moth caterpillars while they are feeding,
- 16 oz
- Easy to use in any kind of sprayer
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.