Q: Yellow jackets are a big pest problem in the fall. They're busy swarming just when people are out tidying the landscape and hauling brush. What's the best way to control them?
A: Yellow jackets are usually more numerous in the fall. They are also more defensive as they are preparing for winter. Yellow jackets overwinter as adults in many parts of the country, unlike paper wasps, which die out every year.
There are a number of ways to combat yellow jackets. Traps are effective but will not catch all of the yellow jackets in a colony, leaving a good many to continue to be a nuisance. The best method is to kill the colony. If you can't find the colony, puff a little flour on a yellow jacket and it will head directly back to the nest, allowing you to follow it. You should obtain a bellows duster to apply the flour. Once you find the nest, you can make plans to attack it at night when the yellow jackets are quiet.
If there are entrance holes in the ground, you can simply place a clear, glass bowl over the holes, which will prevent the yellow jackets from leaving the nest and cause them to starve. Make sure you find all of the entrance holes before doing this.
If you decide to use a pesticide to kill them, don a bee suit and go to the site at night. Prop a flashlight on one side of the entrance hole and turn it on. Then inject an insecticidal dust or diatomaceous earth into the other side of the entrance hole. Some of the yellow jackets will come out before dying and attack the flashlight. Then quickly plug or cover up the hole to prevent any more from escaping. (If the nest has two entrances, quietly cover one of the entrances with a rock or board before treating the other entrance. Don't throw dirt on the entrance you want to cover or do anything else that could alarm them.)
If you have raccoons or skunks in your neighborhood, you can pour some honey next to the entrance holes. The animals will be attracted to the honey and will dig up the yellow jackets nest to get to the brood, which they relish.
If you want to trap them, one simple trap is a plastic jug or jar with some Kool-Aid or apple juice in the bottom. The yellow jackets will get in but will be unable to get out. You can also punch a quarter-inch hole in a plastic jug and put a piece of liverwurst in it. The yellow jackets will enter the jug but will not be able to get out. When the jug is full, you can dispose of it and the yellow jackets.
It's best if you do not invite yellow jackets into your yard to begin with. Don't leave trash uncovered or leave pet food out overnight. Pick up any empty soda or beer cans or glasses and don't leave ripe fruit lying around.
(Send questions for Richard Fagerlund to University of New Mexico Environmental Services, Physical Plant Department, 1818 Camino del Servicio N.E., Albuquerque, NM 87131-3500 or e-mail firstname.lastname@example.org. For more information visit www.askthebugman.com)