For a critter that's been around this country quite a few years, the gypsy moth certainly is elusive when you try to get some information on it.

Among my dozens of garden books and magazines I found only two or three woefully inadequate references to gypsy moths. A number of phone calls later, I'd learned a few facts:

Gypsy moths are a real threat to this area in the next year or longer, but no expert was willing to say just how much of a threat. In other words, we may get a major infestation as soon as next spring, or we may not. What the experts do know is that Pennsylvania has been hit by the pests -- some parts of the state quite severely -- and the moths tend to move on, in this case southward. Evidence of the presence of gypsy moths in this area was first spotted two years ago with the arrival of some male moths.

While gypsy moth caterpillars are voracious eaters and will consume the foliage on just about any tree, the caterpillar's favorite food is white oak. Maryland, Virginia and the District have a large population of white oaks.

Because they aren't native to this continent, gypsy moths have few natural enemies. The gypsy moth caterpillar -- the real pest, since it's in this stage that the insect munches away -- is a brownish creature sporting blue and red spots on its back and long, prickly bristles all over its body. Birds are not fond of the caterpillar, according to a spokesman for the Department of Agriculture. There are a few rodents that feast on the insect but generally, biological controls are hit-and-miss. Researchers are experimenting with parasites and diseases deadly to the gypsy moth at different stages. Many jurisdictions will have programs to release these weapons under careful supervision by experts.

According to the USDA spokesman, the most effective control device in other parts of the country has been spraying. There are several chemical sprays along with BT (bacillus thuringiensis), a pathogenic bacterium deadly to many insect pests in their larval stage, but safe for man and plant life. Many area gardeners are already familiar with BT's high rate of effectiveness against tent caterpillars and cabbage loopers.

It's unlikely, according to the USDA, that a single homeowner can do much to control gypsy moths on his property. Right now, the insects are in their egg stage; small and large masses of eggs are forming on trees, in brush piles and on fallen or decaying branches. They attach themselves to almost anything outdoors that's likely to remain undisturbed for some time. This is not to say that these egg masses are everywhere, but they're very difficult to spot. Experts recommend that gardeners and interested home owners form neighborhood groups, perhaps through a garden club, and present a united front against the potential problem. Call your local extension agent to get more information and ask him what you can do to help keep the caterpillars from damaging your trees. MORE TREE CARE: You may not be able to do much right now about the gypsy moth problem, but this is a good time to tend to fruit trees. Branches that have broken off in fall winds should be properly and neatly pruned below the break and a wound dressing, available at any garden center, should be applied. If hungry goats or scratching animals have destroyed any of the bark, paint damaged areas with wound paint. Cut off dead branches; clean out wounds and apply paint on them. When pruning, make the cut at right angles to the bark to hasten healing. All cuts wider than two inches in diameter should be covered with wound paint. Rotting and dead wood are wonderful havens for many damaging insects. Wrap young trees with special tree wrap or ordinary paper to help keep rodents from girdling them. Mulching is as good for trees as it is for the garden, but keep the mulch two feet away from the trunk. Rodents like to burrow in mulch around trees.