Arsenate of lead was used to fight this outbreak, and soon afterwards, the orioles that had nested in the elms slowly disappeared. The small insect-eating vireos and warblers in the area apparently suffered also.

Thanks to biological controls, the gypsy moth is no longer a pest here, but in the long run, spraying did more harm than good, many entomologists claim. Some 25 parasites and predators were introduced to control the moth, and insecticides allegedly hindered these parasites in establishing themselves in some areas.

When DDT came on the scene after World War II. Cambridge's robin population took a sudden drop. "Once, every morning before dawn, there was a rolling chorus of robins." Walcott noted. "To my cars, there has not been a robin chorus in Cambridge since 1951."

Presumably, DDT reaches the ground on falling leaves, and earthworms surfacing at night accumulate the toxin when they feed. DDT then passes up the food chain to the robins.

The most thorough studying linking DDT to robin kills in New England was done five years ago at Dartmouth. After a "typical" DDT application, the robin population dropped 70 percent. Many robins and other birds were found in convulsions.

However, the same study reported no effect on the robin population after a methoxychlor spraying.

The actual numbers of birds in Cambridge may not have changed much in recent years, but the composition of the population has. At the turn of the century, some five dozen species nested here, including 16 varieties of warblers and vireos. Except for the unsprayed area around Fresh Pond Reservoir, none of these warblers and vireos regularly nest here now. Only half a dozen native species next here in any numbers today. The commonest birds-the starlings, English sparrows, and pigeons-were all imported from Europe during the nineteenth century. Insecticides may account for some of this lack of variety.

HARVARD'S one other spraying program has received a clean bill of health from biologists: B and G uses about 40 gallons of oil on lilacs and about 90 gallons of oil on lilacs and hibernating scale insects. The solution dissolves the insects' protective wax and the petroleum then suffocates them.

Faced with possible adverse side effects of pesticide use. B and G is caught in a tough position. "The trees, shrubs, and lawns are really worth improving." said Donald C. Moulton. Deputy Director of Buildings and Grounds, but "people's disregard" for B and G's efforts to keep Harvard green is increasing, he added.

"How do you keep a laborer interested when a week after planting a lawn it looks like the Battle of the Bulge?" commented another B and G official.

Given this uphill battle to fulfill its groundskeeping task, B and G is understandably cautious about proposals to reduce spraying. Even if such a proposal could produce a more natural ecological balance in the long run, most options to stop spraying run the risk of losing some green plant cover, at least for the first few years.

"You get hooked on these controls or drugs." commented William H. Drury '43, a biologist with the Massachusetts Audubon Society, "and once you stop, you get withdrawal symptoms."