The brown tree snake already has killed off 17 animal species in Guam, including nine of the island's 11 native birds. A sighting on Saipan in the Northern Marianas recently was confrrned. Officials now fear it will get to Hawaii, then the Mainland, hiding on planes and ships.

"What's at stake is the ecology of many islands in the Pacific," says Interior Department scientist Tom Fritts. Likening the snake to a bomb, Fritts says, "The question is, when is it going to go off, causing ecological, economic and sociological damage?"

Tree snakes, native to Australia, originally spread as stowaways on military flights after World War II. They have no known natural enemies outside their native island, where parasites keep them in check. Scientists are reluctant to import those natural enemies for fear that these parasites, in turn, would go unchecked.

Coffee-colored with green tints, the reptiles can grow to 10 feet on tropical islands.

The nocturnal snakes gorge on Guam's birds, bats, rats and lizards. They have wiped out poultry farms and have gone after puppies. They also climb utility poles and transformers, which has caused more than 1,300 power failures in Guam in the past 25 years.

Hospitals there have treated more than 200 people for snakebites. The venom is like a wasp sting to adults, but it's riskier for children.

Clinton's proposes tripling spending on finding ways to control the pest. So far the emphasis has been searching for stowaway snakes on ships and planes that go through Guam. New money, the first since 1990, would boost research to capture and exterminate the pest.

Otherwise, time may run out for Hawaii, where the snake could decimate dozens of endangered species and affect tourism, Fritts says.

Scientists are trying to find natural chemicals to attract snakes into traps or repel them from sensitive areas. They're building snake-proof barriers for warehouses and critical habitat.

A National Zoo pathologist is studying two viruses he hopes could be used to kill the snakes without infecting other animals, plants or humans.