By Gary Salmon
This is the business end of a purple sticky trap. It is a three-sided affair which is suspended from a tree nearly 20 feet in the air. We have all seen these hanging from “trees of concern” to help determine the presence of Emerald Ash Borer. Even our roads in Shrewsbury had traps scattered throughout the town.
They were hung in far greater numbers several years ago when EAB in Vermont was just a theory. It was first detected in Vermont in 2018 and now that it is firmly established, fewer traps are necessary and are now used in “high risk” areas to confirm EAB’s presence as this outbreak continues to invade more and more of Vermont and its ash trees.
The traps themselves are built to capture insects. A lure which smells like ash leaves or ash bark is dangled in the space between the three purple sides (even the color purple is attractive to some insects). A sticky surface is applied to the outside of the trap which will capture insects landing on it. They are suspended during the EAB borer flight season, which starts in late June/early July and the traps eventually reach the lab of a dedicated entomologist who sorts through this mass of insects looking for any EAB borers.
However, most of us only see a purple item hanging in a tree and not the sheer mass of insects that eventually get stuck. These traps will capture any insect that comes in contact with it, not just the ones being searched for.
So trap location is critical as a strategy to success as well. The trap pictured below is hanging in a clump of seriously declining ash trees at Lake St. Catherine State Park in Poultney, a good location to capture EAB if present. So until an area shows the other summer signs of EAB’s presence (a combination of crown dieback and new clumped branches growing right out of the trunk, suckers at the base of the tree, splitting bark, and/or “D” shaped borer exit holes) traps are a good companion tool in locating EAB and by actually capturing borers confirm that EAB is present.