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Farm Advisor: Those Annoying Yellow Jackets

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This article was provided to by Calaveras County Farm Advisor Ken Churches.

San Andreas, CA — Now is the time when yellow jackets become a problem here in the foothills. It helps to become familiar with these stinging insects to be better able to cope with them. Yellow jackets are heavy-bodied wasps, with black and yellow or white markings. They actually live in gray, papery nests, located either below ground or suspended above the ground.

The workers in the colony hunt for insects, or feed on carrion or rotting fruit. They are attracted to any meat-based or sugary item. Food is carried back to the nest where it is fed to nest-mates. Stings usually occur through accidental contact with the nest entrance or by sipping one in your soda can. A nest can grow rather large during the season. By the end of summer, nests may contain hundreds or even thousands of workers. So by August or September, these venomous social insects are the most troublesome and dangerous.

It might occasionally be necessary to destroy a yellow jacket nest because it is near human activity. Here are some suggestions for safe and effective nest removal:

– Treating the nest at night helps because the workers are inside and relatively calm.

– Use one of the aerosols that propel a stream of insecticide “up to 20 feet” so that you can stand off at a safe distance and treat directly into the nest opening.

– Don´t pour petroleum products into ground nests. This is dangerous, environmentally harmful and illegal.

– Use products specifically made for yellow jacket control only. Be sure to read and follow the pesticide product label. The label is the final word on what does or does not constitute a legal and safe application.

Trapping with non-toxic yellow jacket traps that are available in yard and garden stores is a good option. The most effective traps use a synthetic attractant to lure worker yellow jackets into a trap. Fruit juice or various meats can be used as attractants as well. Traps may provide some temporary relief by drawing workers away from people, but they are not effective for area-wide nest control. It is best to start trapping early in the yellow jacket season.

As with most creatures, it is best not to aggravate them by swatting at them or trying to chase them away. Some people are allergic to the venom of yellow jackets and others are allergic to bee stings. Both reactions can be life-threatening to some people. If you are particularly sensitive to yellow jacket venom, be extra cautious in late summer and early fall, when the insects are most numerous. Enlist the help of someone not as sensitive, if you need to spray a nest. If a yellow jacket stings you, remove any rings or tight fitting jewelry immediately in case of swelling.

To tell the difference between a yellow jacket and a honeybee, it helps to watch their behavior. Honeybees gather pollen and flower nectar, while yellow jackets are mostly meat eaters, but will take plant and fruit juices also. Yellow jackets are particularly fond of rotting fruit. Yellow jackets are more likely than bees to sting without provocation, their sting is more painful, and normally no stinger remains in the skin and a single yellow jacket may sting more than once. Honeybees are much less likely to sting and their sting is not so painful. A honeybee leaves behind its stinger and a single bee can sting only once.

Other wasps you may have noticed are the mud daubers and paper wasps. You´ll see mud daubers around wet soil collecting bits to take back to their nests, usually a mud tube. Paper wasps build small, open nests that are suspended vertically from a horizontal surface, such as under an eave. Their long legs and thin “waists” distinguish paper wasps. Both mud daubers and paper wasps are less aggressive and normally will not sting or swarm when away from their nest.

This article adapted from Cooperative State Research, Education and Extension Service, USDA. Please contact the Farm Advisor´s office at or (209) 754-6477 with your agricultural questions. Talk to a certified Master Gardener every Wednesday, 10 a.m. to 12 p.m. at (209) 754-2880.

Ken Churches is the county Farm Advisor and director for the University of California Cooperative Extension.