ST. LOUIS — It does not appear that a beetle species blamed for killing millions of ash trees in the U.S. has spread beyond a county where it was spotted last year to other parts of Missouri, state officials said.
Scientists set traps for the emerald ash borer throughout the state after finding it in southeast Missouri's Wayne County last year, but have yet to see the Asian beetle turn up anywhere else, the St. Louis Post-Dispatch reported Tuesday.
The beetle has been found in 13 states since first being spotted in the U.S. near Detroit in 2002, and it is estimated to have killed nearly 30 million ash trees.
Over the last few weeks, the state entomologist and U.S. Department of Agriculture officials have been picking through more than 1,000 sticky traps set this summer.
Traps were placed around Greenville Recreation Area at Lake Wappapello, where the first infestation was discovered. Workers thought the beetle would travel on firewood, so crews also set out traps at campgrounds and parks as far north as Maryville and as far south as Table Rock Lake.
About half of the state traps had been searched by Friday, with no sign of the emerald ash borer. The same held true for traps set by federal workers.
"The traps are just one tool we have to help us identify the boundaries," said Mike Brown, the USDA's state plant health director.
"I think what we're seeing just really speaks to how difficult it is to find new infestations."
In Missouri, ash trees make up about 3 percent of the state's forest. But that number is higher in urban areas, where 14 percent of street trees and 21 percent of trees in parks are ash.
Ash trees have no defense against the borer, whose larvae disrupt the tree's vascular system, killing it from the inside.
Missouri conservation officials aren't recommending landowners outside the infestation area cut down ash trees, but they say proper tree care is important.
They also advise against buying firewood that was cut more than 50 miles away from where it's used. They also suggest campers burn all the firewood they bring into an area rather than carrying it home, because that's the borer's main way to travel between locations.