Human Nature.(The Talk of the Town)(United States Department of Agriculture on pest control)

The red imported fire ant, or Solenopsis invicta, is about an eighth of an inch long, with a ruddy-brown body covered in tiny hairs. It feeds mainly on other insects, but will eat just about anything--including electrical equipment--and is reportedly drawn to dirty laundry. A mature colony can contain as many as two hundred and forty thousand individuals and every year produces several hundred potential queens. These queens mate just once, during their "nuptial flight," then snap off their wings and go looking for a suitable site to start a new colony.

Native to South America, red imported fire ants probably arrived in the United States in cargo ships that docked in Mobile, Alabama, sometime in the nineteen-thirties. By the late forties, they had spread into Florida and Mississippi; by the early fifties, they could be found as far away as Arkansas and North Carolina. Wherever new colonies appeared, trouble followed. The ants attacked young plants and animals, and in humans their bites produced a painful sting accompanied by white pustules. Their mounds, which grew as high as two feet, reduced agricultural yields and damaged farm equipment.

Among those who watched the progress of the ants with horror were officials at the United States Department of Agriculture. In 1957, the department decided to eradicate the insects. Its weapons of choice were the pesticides heptachlor and dieldrin, both of which concentrate as they move up the food chain. In 1958, a million acres were sprayed. Quails, woodcocks, wild turkeys, blackbirds, meadowlarks, opossums, and armadillos all began dying off. The U.S.D.A. responded by denying any problems and continuing to spray.

Among those who watched the progress of the U.S.D.A. with horror was Rachel Carson. She concluded that the department had never investigated the pesticides' toxicity or, if it had, had ignored the results. (Heptachlor causes liver damage, and dieldrin is a neurotoxin.) The department seemed equally clueless about the basic biology of the ants, which continued to spread even as the chemicals rained down. The war against the fire ants was, in Carson's words, "an outstanding example of an ill-conceived, badly executed, and thoroughly detrimental experiment in the mass control of insects"; it became one of the inspirations for her book "Silent Spring."

Carson was born a hundred years ago this Sunday--on May 27, 1907--in the town of Springdale, Pennsylvania, just outside Pittsburgh. As a child, she fell in love with the sea, although she had never seen it. She went on to earn a master's degree in zoology from Johns Hopkins, and became the author of several works about ocean life, including "The Sea Around Us," which won a National Book Award in 1952. "Silent Spring," much of which was first published in this magazine, came out in 1962. It was her last work; she died, of breast cancer, eighteen months after it appeared.

As much as any book can, "Silent Spring" changed the world by describing it. An immediate best-seller, the book launched the modern environmental movement, which, in turn, led to the creation of the Environmental Protection Agency, the passage of the Clean Air, the Clean Water, and the Endangered Species Acts, and the banning of a long list of pesticides, including dieldrin. Depending on how you look at it, Carson's centenary couldn't come at ...