Emerald ash borers are dark green beetles native to China and eastern Asia that kill ash trees by laying their larvae underneath a tree's bark.
Officials believe they accidentally arrived in North America in wooden shipping materials. The first reported signs of emerald ash borers in the United States were in southeastern Michigan in 2002.
In Pennsylvania, the ash borer was first discovered in Butler and Allegheny counties in 2007 and has since been spreading east slowly but steadily. It could arrive in the Lehigh Valley in a matter of months.
The Pennsylvania Department of Agriculture says the invasive pest has been newly discovered in both Wyoming and Huntingdon counties, bringing the total of ash borer-infested counties in the state to 21.
While the state urges residents to try to quarantine the borer, officials believe it will eventually make its way into Northampton and Lehigh counties, moving toward New Jersey.
"The thought is that if it's not already there, it's on its way," said Pennsylvania Department of Agriculture Deputy Press Secretary Nicole Bucher. "But we are trying to slow the spread , not just in Pennsylvania but to other states as well."Bucher said she expects to find positive samples of ash borer presence in the Lehigh Valley area by year's end. To combat the spread of the borer, officials in Harrisburg are urging Pennsylvania residents not to transport firewood more than 50 miles from where it was originally purchased.
For tracking purposes, the Department of Agriculture has hung more than 2,000 triangular purple boxes on ash trees across eastern Pennsylvania. They attract adult flying beetles, allowing the state to track them.
While New Jersey has had no reported signs of the borer, officials in the Garden State are cautious.
Rosa Yoo, assistant regional forester for the New Jersey Department of Environmental Protection, said the beetle seems to be headed east rather than south, putting New Jersey in danger.
Yoo says the DEP has hung more than 600 of the boxes seen in Pennsylvania in the northern half of the state. She said they are monitored for traces of the borer and will be examined by the end of August.
The state is also echoing Pennsylvania's call not to transport firewood.
New Jersey is in a difficult spot to resist the spread of the borer, according to Yoo, because reported signs of infestation in both Pennsylvania and New York leaves New Jersey fighting a two-front war against the pest.
So when will the emerald ash borer make its way to the Lehigh Valley and beyond? Officials say there's no way of telling for sure but that with preventative and reactive measures taken by the community it will be easier to stop the spread.