Q: I heard you describe on your radio show how to construct a trap for Asian ambrosia beetles. I think the parts were a soft drink bottle and Purell hand sanitizer. Where can I find specific instructions to create this trap?
A: I have become personally interested in Asian ambrosia beetles ever since they killed a big flowering cherry in my back yard. I fear they will become a big problem as the years pass because they bore into healthy trees. The female beetles introduce a deadly fungus into the center of a tree. Besides cherry, they also attack crape myrtle, Japanese maple, redbud and many other trees.
Susceptible trees can be protected with an insecticide spray on the bark when beetles are present. Because it is hard to predict when the beetles will emerge in spring, a monitoring trap is a good tool. It won’t lure all of the beetles but it does help pinpoint when to spray.
Hang traps Feb 1.
Asian ambrosia beetles are attracted to ethyl alcohol (not rubbing alcohol) vapors. Cut a big hole in the side of a 2 liter soft drink bottle, leaving at least an inch at the bottom of the bottle untouched (see below). Put 2-3 squirts of Purell hand sanitizer in the bottom of the bottle and hang it near a susceptible tree. Monitor it daily for tiny black beetles stuck in the Purell.
Another simple trap is made from a bolt of wood with a hole drilled down the center. Any hardwood will work, and a branch 2” – 4” in diameter, about 2 feet long will do the trick. Drill a ½” (+/-) diameter hole down the center as far as you can (but not all the way through) and fill it with ethanol (grain alcohol, not rubbing alcohol; denatured is OK). Put a stopper of some sort (a cork, for instance) in the hole and then hang the bolt about waist high at the edge of the landscape. Monitor weekly. Beetles, if present, will begin producing telltale toothpicks.