Minnesota Uses Arsenal of Creative Tactics on Tree Killing Beetles

By Dennis Lien

Twin Cities, MN (July 1, 2012) – As public officials in Minnesota enter their fourth summer battling the invasive Emerald Ash Borer that threatens the state’s nearly one billion ash trees, they’re employing a creative and experimental array of strategies to identify and kill them before they become established. While it’s still early in the season, no emerald ash borers or infested trees have been discovered in Minnesota so far this year.

In addition to the more traditional visual inspections and tree-removal efforts, Minnesota is using the STUC (Sticky Traps Using Cadavers) approach. Elsewhere, four dogs are being trained to sniff out ash and EAB-infested ash. About 6,500 purple detection traps have been placed in uninfested counties around the state. And 25,000 stingless wasps that lay eggs in EAB larvae and kill them have been released.

“We’re doing everything we can think of,” said Mark Abrahamson, the agriculture department’s EAB project manager. “It’s a big problem, and there aren’t any easy solutions. Minnesota has a lot at stake because we have a lot of ash trees.”

It’s difficult to assess the specific impact of each one. But collectively, this much is clear: While early in the season, no emerald ash borers or infested trees have been discovered in Minnesota so far this year.

STUC involves applying glue to an ash tree leaf, attaching a dead female emerald ash borer to the leaf, then spraying a sticky substance over the insect. Ideally, any male emerald ash borer looking to mate would be attracted to the dead beetle or others, land, and become permanently stuck. That way, their movements could be detected earlier than late.

Found first on the western edge of St. Paul in 2009, emerald ash borers were later found in a couple of other spots in Ramsey County, in eastern Hennepin County and in Winona and Houston counties in the extreme southeast part of the state. All of those counties are under quarantine, meaning ash and hardwood firewood cannot be moved out of them into nonquarantined counties.

So far, 500 to 1,000 ash trees have been infested by the beetles and removed in the two metro counties. About that many also have been found to be infested in the two southeastern counties. Many of them, especially accessible ones along roads, have been removed.

“It’s an easier bug to deal with in an urban area,” Abrahamson said. “It’s a problem, but it’s one which we have done about as good as we could expect to.”

In neighboring Wisconsin, there’s been much more activity. Just last month, the invaders were found in at least eight new locations and have now been found in 12 counties, including some just across the Mississippi River from southeastern Minnesota.

Related Resources:
Pioneer Press, “Student uses dead beetles to track movement of insect infestation
Emerald Ash Borer Poses Danger to Nearly Half of Morris’ (MN) City Trees
Emerald Ash Borer Creeps Towards Connecticut
Emerald Ash Borer Network