Carol McQueney, age 12, of Manheim, Pennsylvania, for her question:

What is the story of the Japanese beetle?

Most insects have favorite foods and stick t'o a menu of dust a few related plants. Not so the Japanese beetle. This insect pest attacks at least 275 different plants and the damage it does every year is estimated at $20,000,000. It is not a native North American insect and the first arrivals came sometime before 1916. Since then, its story has been success for the beetles and disaster for our plants.

In 1916, a few strange insects were noticed in a nursery near Riverton, New Jersey. They were stiff, oblong beetles with coppery wings and metallic green bodies bordered with a dozen small white dots. At the time, nobody regarded these first arrivals as a serious threat. After all, they were only half an inch long. Experts traced them to their native home on the main island of Japan and assumed that they had hitched a ride to North America on some Japanese nursery plants.

It soon became obvious that the Japanese beetle was a serious menace. What's more, the creature made himself at home here, thrived and multiplied at a great rate. From early fall until the following June, its grubs devoured grass roots, ruining lawns and pasture. During the summer, the adults devoured the leaves and blossoms of garden plants and ornamental trees, field crops and orchard trees. In a few years, the early arrivals had become countless multitudes    and spread from state to state.

Experts studied the Japanese beetle hoping to find a weak spot in its life cycle. But by then it was too late to control them. The adults appear in late June and live only a couple of months, during which time they do enormous damage to the vegetation. They are strong fliers and deposit their eggs in the soil, far and wide. The grubs hatch. in about two weeks, burrow down and gorge on roots through the winter and spring.

In May or early June, the greedy write grubs become pupas and the adults hatch in late June. Various insecticides were used to control the adult beetles and a bacteria was found to attack the grubs in the ground. Some of the insecticides have been discarded as dangerous.

But the milky disease caused by the bacteria has proved to be a safe and effective way to wipe out the grubs.

However, regardless of all our efforts, the Japanese beetle now infests the central states along the Atlantic seaboard, spreads south as far as Georgia and west as far as Missouri. It does less damage in certain years, but this may be due to the weather. In the eastern states, the average summer rainfall is about 12 inches. When a dry season brings as little as eight inches, many eggs and small grubs are destroyed. The following year, fewer adults do less damage.

Winter climate seems to limit the range of this insect pest. The grubs need fairly moist soil, preferably under a warm blanket of winter snow. The average winters of Canada and New England may prove too cold. The western regions may prove too dry. The grubs might survive where dry fields are irrigated but they could not survive on the open prairies.