BUG SLAYER

Reginald Colley '09 tried to find a disease that would kill a major forest pest. eighty years later, his experiment succeeded.

IN JUNE OF 1989, entomologists across the Northeast were baffled by a strange disease that was killing off gypsy moths in unprecedented numbers. The leaf-eating caterpillars, brought from the Far East in the nineteenth century, had been a scourge to broad-leaved trees for many decades. Their populations would soar and crash in fairly regular cycles that varied only with changes in the weather. The spring of 1989 was supposed to be a big season for the gypsy moth, but throughout the Northeast the mysterious ailment was keeping numbers far below the disastrous levels of past outbreaks. Caterpillars were dying in New Hampshire, Vermont, Massachusetts, Connecticut, New York, New Jersey, and Pennsylvania.

The scientists finally isolated the disease a fungus called Entomo-phaga maimaiga and they managed to trace it back to a Dartmouth grad who had cultivated it nearly 80 years before. The discovery is one of the most remarkable stories in the history of insect science: an entomological "time bomb," say researchers, that may save millions of acres of forest trees. But like Gregor Mendel, whose foundations for the science of genetics remained unrecognized until 16 years after his death, the champion of the gypsy moth disease was not destined to know that his experiment had succeeded.

The experimenter was Reginald Hunter Colley '09, a biology major who was to go on to teach at Dartmouth from 1910 to 1916. First, however, he went to Harvard to get a master's degree. It was there that he and plant pathologist Arthur Speare attempted to find a natural weapon against gypsy moths.

The insect had already been devastating American forests for almost half a century, having been accidentally released in the 1860s by a Boston entomologist who had hoped to breed it with silkworms. The pest gradually spread throughout the Northeast and eventually traveled as far south as the Gulf of Mexico and as far west as California and Oregon. The moth's larval stage chews on the leaves of deciduous trees; three or four successive years of attack can kill a tree. In 1981, the worst year on record, the insect defoliated almost 13 million acres of forest, according to the U.S. Department of Agriculture.

Although the pest had not nearly reached that stage of destruction in 1910, it was serious enough to inspire Colley and Speare to cultivate a mothkilling fungus brought over from Japan by another researcher. The disease had traveled inside the bodies of a group of gypsy moths, but the hardships of the trip to New England had killed all but two of the caterpillars. The two young scientists put the insects in a moist culture dish, then in an experimental "infection" box, arranging them so the spores would be discharged onto healthy caterpillars. By the time the disease was sufficiently prevalent in the experimental boxes, however, almost all the larvae in the field were busy turning themselves into moths too late to release the disease.

Undiscouraged, Colley and Speare put healthy gypsy moth caterpillars into the boxes, and through the germination of resting spores, the new larvae were reinfected. That summer, the researchers "planted" the larvae in six suburbs of Boston. They wrote up a paper that was published two years later, and then seemingly forgot about the whole thing. For the next eight decades the fungus had no apparent effect on gypsy moth populations or so scientists thought, until they rediscovered it last year. "Somewhere in between 1910 and 1989, something must have been happening," says Richard A. Humber, a USDA microbiologist in Ithaca, New York, who helped iden tify the fungus. "It could not have been completely inactive during this whole time." He believes the disease, which multiplies inside the caterpillar and then literally consumes it, existed in low levels in the decades between Colley's experiment and its subsequent success. Humber suspects a combination of a growing population of gypsy moths and an unusually cool, wet spring finally altlowed the fungus to take hold.

"It's pretty overwhelming when you stop to think that something released in as low a quantity as two affected organisms 80 years ago has now covered an entire region of the United States," he says. "I can't think of any other kind of diseases where there ended up being this kind of a time bomb."

Through a remarkable stroke of bad timing, however, Reginald Colley was not around to see it go off. He had died at the age of 101, just four months before the rediscovery.

He did not die a disappointed man, however. For one thing, the gypsy moth experiment did not seem to occupy his thoughts for very long. He didn't have time. The Nova Scotia native had led a remarkably active life ever since he had worked his way through Dartmouth. He graduated cum laude with honors in biology and went on to earn his Ph.D. in plant pathology from George Washington University. "I think the moth experiment was a stage of his life he had more or less put behind him," says Rowena Wangenheim, youngest of his four daughters. In 1928 after 12 years as a forest pathologist with the Department of Agriculture, Colley joined Bell Telephone Laboratories in New York City. As head of the timber products division, his job was to investigate ways of keeping termites from destroying telephone poles. In 1986 the American Wood Preservers Association, of which Colley was a past president, created a lecture in his name. It was said then that his contributions to the field were "too numerous to list."

As if insects didn't keep him busy enough, Colley mastered the cello, wrote poetry, and acquired seven or eight foreign languages. Even in the nursing home that he was finally forced to enter at the age of 98, he surrounded himself with his grammar books and read The New York Times front to back with a magnifying glass. As one of Dartmouth's oldest living alumni, Colley led the parade on his 70th Reunion in 1979.

It is ironic that what may have been his life's most important contribution escaped his own notice. "It was a real tragedy that he didn't know," says Richard Humber.

But it was also characteristic, in a way The man whose experiment was 80 years ahead of its time also died albeit at an impressive old age ahead of his time.

Colley showed brass evenas an undergraduate.

He died at the age of 101, just four months before the rediscovery.