Learn all about yellow jackets.
Most of us view yellow jackets as major pests. However, some of the species help us by feeding on aphids, caterpillars and other garden pests, while the rest play a beneficial role as nature's cleanup squad. We'd probably be neck-deep in dead meat without their help. Still, it is hard to be grateful to these critters when they are commandeering your forkful of grilled chicken or delivering a painful sting. And unlike honeybees, these yellow-and-black wasp relatives can sting repeatedly. That sting, plus their "meat and sweet" diet, can add a certain element of tension to fruit picking and fine dining in the out-of-doors.
Most people wait until numbers build up before putting out yellow jacket traps, but trapping in April and May is actually more effective in many areas. Although yellow jackets (Vespula species) are social insects like honeybees, they use their nests for only one season. All the workers and drones die off in the fall and responsibility for propagating the species is left to the newly hatched and fertilized queens. In late fall, the queens crawl into forest leaf-litter or some other protected site. Insulating leaves, snow and an ability to "super cool" protect the ladies from sub-zero temperatures all winter. Come spring, they emerge and start a new nest, often in a mouse or vole tunnel. Until the first batch of workers hatches, the queen must forage for all the food herself, and this two- to three-week period is when she is vulnerable to being trapped. Every queen killed now may eliminate several thousand yellow jackets later in the season. (The pa per wasps that nest under the eaves are not usually picnic pests, and are great caterpillar hunters, so unless the nest is near a doorway, it's best to leave them be.)
Weather during this spring period also may be a crucial factor in whether a particular season proves to be a "bad" yellow jacket year. A severe cold snap just after the protective layer of snow has melted could kill off many queens still in the ground, thereby reducing the number of prospective nests. A prolonged wet spell could hamper the queen's ability to set up a nest or forage, resulting in fewer bees per nest. On the other hand, a consistently dry, warm spring allows huge numbers of dormant queens to wake up comfortably and successfully go about their business.
Other natural factors also may be at work locally—one summer night we had a black bear carefully search and destroy at least eight nests in our one-acre orchard. Nothing was left the next morning but holes in the ground and a few forlorn bees. However, failing bears in the neighborhood, spring trapping may be a more dependable method of control.
Both homemade and commercial yellow jacket traps (available at most garden stores) can be effective. One expert suggests bologna and apple juice to attract the bees, and others swear by tuna-flavored cat food. Some commercial "attractants" claim to lure in the queens particularly well. The best bet is to experiment for several seasons to see what works most effectively in your particular area. Whatever you use, empty the traps and refresh the bait every few days. Yellow jackets dislike the smell of rotting meat, including rotting dead yellow jackets. Place the traps out of direct sunlight in an open area and away from where you plan to be active. Random insecticide spraying will do nothing to control numbers. However, a direct shot can kill a nest of yellow jackets, if necessary. Work very carefully at night when the yellow jackets are home—and have an escape route planned!