August 13, 2004




Take a glance at the picture on the right and file in your memory the image of the light colored moth and buff egg mass shown in the circle inset. This is the gypsy moth female and egg mass that is common in all areas of the north at this time of year. Gypsy moth has become a common pest of the northern forest during the last decade and the insect continues to spread west ward since its introduction into the United States over 100 years ago. The presence of gypsy moth is the result of an experiment gone sour. In an attempt to culture a superior species of worm that would produce silk, gypsy moth escaped and found the forest of America to its liking.

Its distant kinship to the silk worm explains why you will encounter sheets of tiny threads hanging from trees in the woods during June and July. Attached to the end of the tiny threads will be the worms that hatch out of the egg mass shown in the above picture. In addition to the threads in the woods, mushroom hunters often report "rain" in the forest on cloudless days. The rain is actually droppings from the worms (larvae) as they eat the leaves of forest trees. Gypsy moth is within a group of pest called defoliators because they have huge appetites for leaves. Know to eat the leaves of more than 500 species of plants, gypsy moth are real fond of oaks, maple, aspen, and most other deciduous trees of the northern forest. Defoliation of the same tree (forest) in successive years will often cause mortality of the tree but in most cases it is the nuisance of the critter that ‘bugs’ the vacationer or northern home owner.

August is the time of year for the female to lay her egg mass and only last week, I walked behind the garage and picked up a board in a stack of lumber and caught the female in the act. A fresh egg mass was being formed complete with the final layer of ‘fuzzy’ stuff she picks off her body to coat the pile of eggs. One female can lay up to 500 eggs and surprisingly almost every egg in the mass will hatch in the spring.

Gypsy moth will attach an egg mass within any available crack or crevice and this is why the critter has spread so rapidly in the last 30 years. As America’s fondness for vacation and the automobile has matured the gypsy moth gets a first class ticket from cabin site or camp areas to unknown destinations at the end of the tourist season. Aside from the nuisance of the critter, you may not experience any ‘capital loss of valuable assets’ if a gypsy moth hooks a ride south (or north) on the underside of your camper but if you can find the egg masses then you have the key to control the later life stage of the critter. Simply scrape the eggs into a can half filled with soapy water and allow to set a couple days then dump the water on the ground. The treatment is neat and easy and environmentally safe. Once the eggs are removed from the protective insulation of the fuzzy stuff, most will freeze out with the coming winter.

So keep an eye open for this exotic pest that is well on its way to being a naturalized citizen of America’s forest. For more information on gypsy moth check out the web sites of the Michigan DNR at www.michigan.gov or www.entm.purdue.edu/Entomology.

And remember, questions on Northern Living can be directed to www.proforestcare.com.