"It wasn't a good day," said Clint Burfitt, with the Utah Department of Agriculture and Food. "We're asking the public to watch for these insects and to help with eradication."

For the past 10 years, traps throughout the state have turned up empty. Then came the recent call from a Utah County extension agent who had spotted a Japanese beetle in her front yard. Traps indicated the infestation was confined within a 2-square-mile area in Orem, stretching from 800 North to Interstate 15, along 400 South to State Street. State officials asked homeowners in the area to monitor and use a variety of pesticides or biological methods to treat infected lawns, trees and gardens.

But the sighting means there's also a potential for the voracious beetles to eat their way through lawns and plants along the entire Wasatch Front. Such a widespread infestation could require a quarantine on Utah nursery products in an industry that rings up $43 million in annual sales.

The Orem infestation is small, said Clair Allen, director of the state's Division of Plant Industry, adding, "we're doing everything we can to keep it that way."

The infestation may have come from a grub burrowed into an out-of-state tree root or other imported nursery stock, said Ryan O'Shea, a state agricultural technician.

Adult beetles feed on the foliage of plants, along with many species of ornamental and fruit trees during the summer. Females burrow about 3 inches into the ground, laying from 40 to 60 eggs. The eggs hatch in the midsummer and the young grubs begin to feed. In late autumn, the grubs burrow 4 to 8 inches into the soil and remain inactive through the winter. The grubs again feed on roots in early summer until the pupae become adults and emerge from the ground.

Adults, active during the summer, are less than a half-inch long and have a shiny, metallic-green body with bronze-colored outer wings. The beetle also has six small tufts of white hair along the side and back of its body, under the wings.

The pest, which originated in Asia, was first found in New Jersey in 1916 and thrived without natural enemies. Until recently, U.S. infestations had been confined east of the Mississippi River.

Today the beetle is the most widespread turf-grass pest in America. Efforts to control it are estimated to cost more than $460 million a year, according to the U.S. Department of Agriculture.