RANDOLPH, NY (AP) -- A tree-killing beetle first confirmed in New York last year has spread to more woodlands in the southwestern corner of the state.

The Department of Environmental Conservation says the new infestation of emerald ash beetles is within the previously established quarantine area in Cattaraugus County.

The destructive little beetles kill North American ash trees. It was first discovered in Michigan in 2002, and has since spread to 13 states. It's responsible for destroying 70 million trees in the U.S.

New York has more than 900 million ash trees, representing about 7 percent of all trees in the state. All are at risk if the invasive pest becomes established.

Residents can help prevent spread of the ash borer and other destructive tree pests by buying camp firewood from nearby sources rather than bringing it from home. You can also use firewood labeled as meeting heat-treating standards.

(Copyright ©2010 by The Associated Press. All Rights Reserved.)