A long-horned beetle of the genus Stenhomalus, which has been intercepted only once before in a U.S. port, is not yet known to be loose in North America. But the insect belongs to a family of highly destructive wood-boring beetles whose members have escaped from foreign cargo and are now defying federal quarantines in New York, New Jersey, Illinois and other states. Cousins of the bug captured in Baltimore, including the Asian long-horned beetle, the emerald ash borer, round-headed borer and metallic wood borer, with no native predators to slow them down, have killed tens of millions of trees in North America. They are poised to destroy even more, potentially eliminating entire tree species from the continent, said a Maryland entomologist. 'There are massive programs to eradicate these pests that involve chopping down literally tens of thousands of trees, and hundreds of thousands of applications of pesticide to arrest this thing,' said Mike Raupp, an entomologist at the University of Maryland. Forty-thousand ash trees in Maryland have been cut down in an effort to stop the emerald ash borer here. 'These guys (the Customs and Border Protection agents) get a giant pat on the back,' Raupp said. 'They have stemmed the tide for a little while longer, but, by golly, the deluge is on. Their finger is in a very leaky dike right now.' The Stenhomalus beetle was discovered Aug. 28 during an inspection of a 'general commerce' container in a bonded warehouse at Dundalk Marine Terminal, according to Steve Sapp, a spokesman for U.S. Customs. Agricultural specialists had spotted signs of borers in previous shipments of bark baskets from China and asked that similar shipments in the future be inspected. A warehouse employee spotted the beetle in the first shipment set aside for a closer look. 'He captured it and turned it over to our officers, who notified agricultural specialists. They responded to the scene, preserved the insect and turned it over to the U.S. Department of Agriculture identifier in Baltimore,' Sapp said. This week, the U.S. Department of Agriculture identified it as Stenhomalus and determined it was a 'quarantine-significant voracious wood borer.' The container was fumigated. 