Q: I heard you describe on your radio show how to construct a trap for Asian ambrosia beetles. I think the parts were a plastic cup, a film canister, a cotton wick and alcohol. Where can I find specific instructions to create this trap and what kind of alcohol do I use?
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 two inch holes in a plastic cup and make an alcohol dispenser to place inside by putting wick in a film canister. Keep water in the bottom of the cup at all times. You can find specific directions at How to Make an Asian Ambrosia Beetle Trap.
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 will begin producing telltale tootpicks.