Yellow jackets become more aggressive this time of the year. The population of nests is highest during the fall, increasing demand for food. Because colony members protect the food source in the nest, anything intruding into the nest area will be stung.
Yellow jackets often are mistaken for bees, but they are actually wasps with distinct yellow and black markings. Like other wasps, they make a paper nest, usually underground in stump holes, stumps or under shrubs. Occasionally yellow jackets will nest in attics, old cars or in walls of buildings.
A yellow jacket colony begins in April or May when the queen emerges. The queen is the only member of the colony that can survive through the winter. She finds a nest site, builds a small paper nest and lays eggs that mature into adult workers. Once the queen has produced enough workers to take over nest-building and foraging duties, she stays in the nest producing more offspring. The workers assume all tasks of nest expansion, including foraging for food, defending the colony entrance and feeding the queen and larvae.
By late summer, a yellow jacket nest will have about 800 workers. This is the time of year most people find the nest because of large numbers of workers entering and leaving. It’s also when the next generations of queens are produced. They eventually leave the nest for mating flights. Fertilized queens seek a protected place such as a brush pile, hollow tree or building to spend the winter while the males die.
The current nest will be abandoned by winter and usually is not used again. Nests have been found in Alabama and South Carolina that have been used for many years. These nests, however, have many queens and thousands of workers. One of the largest Southern yellow jacket colonies was discovered in Charleston County, S.C. and contained an estimated 250,000 workers.
There are several things you can do to protect yourself from yellow jackets. Keep in mind that the yellow jackets are often searching for food during this time of year. Many people have been stung when they took a drink from an uncovered cup or can. Garbage cans also attract yellow jackets. Keep lids on garbage cans when possible. Remember to use caution when walking in the woods because nests might be located underground or in a hole.
If a large number of workers are circling an area, the nest entrance can be located by following the yellow jackets’ flight pattern. If the nest is located in an area that does not pose harm to people, leave it alone. Yellow jackets are beneficial insects preying on many insects that we consider pests, especially caterpillars. If the nest is in an area that endangers people, it can be treated with an insecticide.
The best control is to apply an insecticide specified for yellow jacket control directly into the nest opening. Follow all label directions. Insecticides should be applied late evening or at night when all adult workers are inside the nest. The nest entrance should be identified and marked during daytime. A quick knockdown insecticide, containing pyrethrin, is preferred because yellow jackets might fly out to defend the colony when disturbed. These sprays are designed to produce a 10 to 20 foot stream of spray.
Yellow jackets are attracted to light, so do not use a flashlight while applying an insecticide to the nest. Check the nest entrance the next day for activity and reapply again if necessary. If daytime control is necessary, wear protective gear including a hat, veil, coveralls and gloves, because returning workers likely will attempt to defend the colony.
Do not pour gasoline down the hole. This is extremely hazardous and is environmentally unfriendly.