Expert describes steps to curb gypsy moth worms
Weymouth, Mass. — I had seen them for the first time last year on the trunk of my apple tree. Now I was getting another close-up look at one of the furry little creatures as Paul Kruger placed one on my hand.
He was a handsome little fellow, crawling quickly all over my hand and arm in search of food. And that is society's complaint against him: He's a voracious eater.
As the offspring of the gypsy moth, he can eat as many a seven leaves a day. Multiply that by several hundred thousand in the case of a severe outbreak and you can readily understand how acres of trees can be fefoliated and destroyed -- 5.1 million acres of hardwoods in 20 states during 1980 alone.
The unhappy prognosis is for still greater damage this year.
Currently, the gypsy-moth infestation extends from the Northeast coast to the borders of Minnesota, Iowa, and Missouri, and in Washington, Oregon, and California. Isolated sightings haved been made in several other states as well.
"Only the extreme Southern states are immune from attack," Mr Kruger points out, because the eggs require a minimum of two months of very cold weather if they are to hatch.
But all is not doom and gloom. The purpose of my early-morning meeting with Mr. Kruger recently was to hear the message of hope the entomologist with the J. T. Baker Chemical Company is promoting. It is this: The individual is not helpless against onslaughts from this pest, and there is much he can do to protect his own property by using natural biological controls that do not damage the environment.
What is involved is a spray and a mechanical trap for the worms; a pheremone trap for the adult moths; and finally, some good housecleaning during the fall and winter.
The steps to take are:
1. Inspect your trees. The worms have been hatching during the past few weeks and the current crop will range from minuscule dots to almost an inch in length. You won't always see the worms. When small they often hide during the day and feed at night, so check for little pin holes in the leaves.
2. If you see any telltale signs, spray the lower branches with an insecticide based on bacillus thuringiensis, a naturally occurring foe of all moth-derived larvae. After eating some of the sprayed leaves, the caterpillar stops eating immediately and dies within 48 hours. Why only the lower branches? Because the caterpillars, moving up from the trunk of the tree, start consuming the lower leaves first, a comforting thought for someone faced with treating a tree that is 40 or more feet high.
The spray remains potent for up to two weeks. Rain will not wash it off provided it has had time to dry before the rain shower. Some brand names of this natural insecticide are Bag-a-Bug Gypsy Moth Spray, Dipel, and Thuricide. All are available from most garden centers. (Incidentally, they are also effective against all caterpillar enemies of your vegetable garden).
3. Tie a band of burlap around the trunk of the tree. Tie it tightly at the top but leave it loose around the bottom. At dawn, when the worms crawl down the tree to get away from birds, wasps, and other predators, they crawl under the burlap to hide. Take the burlap off every day and shake it over some hard surface.Tramp on the worms and replace the burlap around the tree.
Another option is to wind sticky fly-catcher tape around the tree which ensnares the larvae on their downward journey each morning. The problem with this approach is that other insects that are not your target may get trapped as well.
Toward the end of their caterpillar stage, the worms stay up in the tree, feeding 24 hous a day. Often they reach the size of a man's little finger. At this stage, while tiny wasps will still attack them, lizards and the more numerous birds find them less palatable and will only eat them if they are particularly hungry.
4. Toward the middle of June the caterpillars pupate and emerge over several weeks, the bulk of them just in time to join in the July 4 celebrations. So, set out some pheremone (sex attractant) traps during the last week in June. The traps lure the male moth to the snare with the scent of the female. Hang up the traps from a tree or pole about 4 to 6 feet high.
I am aware of two traps currently on the market, one by the Health Chem Corporation and the other, the Bag-a-Bug Gypsy Moth trap, by the J. T. Baker Company which introduced the highly successful Japanese beetle trap two years ago. One Bag-a-Bug trap is effective over a quarter acre.
5. During the fall and winter look for the furry, beige-brown egg masses that can range up to half-dollar size. The female moth generally lays the eggs on a tree trunk about 4 to 6 feet up. But she will also lay them on any hard object, such as outdoor furniture, your child's tricycle, auto tires, and the sides of campers or cars. In fact, it is campers returning from the Northeast with egg capsules attached to them that have transported the pest to the West Coast where moderate infestations were reported last year.
Biological controls for the gypsy moth are preferred to chemical sprays because chemical sprays in the past have controlled individual outbreaks but failed to stop the plague from ballooning to new heights. This, it is theorized , is because the sprays also have eliminated the moth's natural insect predators -- two species of Wasp and one fly.
The sprays also eliminate other beneficial insects, such as ladybugs, praying mantis, bees, and other vitally needed insect pollinators.