Yellow Jackets – Vespula spp.

by Marcie Crockett
Yellow jackets are social insects that live in colonies containing thousands   of individuals. These wasps will attack aggressively when their nest is disturbed,   and can inflict painful stings. Numerous stings can result in a life-threatening   situation, as can stings to an allergic individual. Unlike the honeybee, which   stings only once and then dies, a single yellow jacket can sting many times.   Yellow jackets are insect predators and can be beneficial when located away   from human activity. Colonies located in or near a home, however, can pose a   threat to people living there. .


SIZE: 5/8 to 1 inch (14-25.4mm) COLOR: Black and yellow or black and white   . They fold their wings lengthwise when at rest. Like all wasps, Yellow jackets   prey on a wide variety of insects and other arthropods. Yellow jackets are unusual   in that workers also forage on foods consumed by people, especially sweets and   meats.

Life Cycle

Yellow jacket wasps live in grey, papery nests located either below ground   or suspended above ground (Fig.2). Colonies usually are started by a single   queen in the early spring, and are very small for the first couple of months.   The life of the yellow jacket nest revolves around the queen whose sole function   is to lay eggs. The queen begins a nest in the spring by laying a few eggs and   raising these workers to adults. At this point the queen will no longer leave   the nest to hunt. Workers provision, expand, and defend the nest all season   long. As spring and summer pass, the nest grows as new workers are reared and   assume their role. By the end of summer, nests may contain hundreds or even   thousands of workers. It is at this time of the year (August-September) that   they are most troublesome and dangerous. By fall the nest also has produced   a crop of new queens and male yellow jackets (drones). By the time of first   frost, most workers and male wasps have died and only new, fertilized queens   remain. New queens leave the nest to find a protected spot to spend the winter.   They reemerge in spring to begin the cycle all over again.

Type of Damage

If a colony is disturbed, worker yellow jackets will aggressively defend their   colony by stinging. For most of us a sting may be just a temporary painful experience,   but for allergic individuals a single sting may result in a serious reaction.   Some people are allergic to the venom of yellow jackets and others are allergic   to bee stings. Both reactions can be life threatening. If you are particularly   sensitive to yellow jacket venom, be cautious in late summer and early fall   when the insects are most numerous.


Management of yellow jacket foragers by destruction of all yellow jackets in   and around an area will reduce the possibility of a dangerous sting. The destruction   of individual colonies may not eliminate all the yellow jacket workers from   an area. Yellow jackets are capable of flying a mile from their colonies in   search of food. Effective management of yellow jackets can be achieved by: (1)   destruction of wasp nests, (2) trapping, and (3) use of physical exclusion from   a food source. The following measures are proven to have no value in reducing   the number of yellow jacket foragers in an area: (1) general spraying of an   infested area, and (2) electrocuting devices employing UV light, i.e., bug zappers.

Control of nuisance nests

It may be necessary to destroy a yellow jacket nest if it’s near human activity.   Nests should be located during the day when the workers are active and the location   of the nest should be marked. Treat nests at night with an approved aerosol   insecticide. Treating at night is safer because workers are inside and relatively   inactive. Use one of the aerosols that propel a stream of insecticide “up   to 20 feet” so that you can stand off a safe distance and treat directly   into the nest opening. These aerosols are called “Wasp & Hornet Spray,”   or something similar. Don’t pour gasoline or paint thinner into nests. This   is dangerous, environmentally harmful, and illegal. Use products specifically   made for yellow jacket control. Some pest control companies will locate and   treat nests for you.


Non-toxic yellow jacket traps are available in yard and garden stores. The   most effective traps for the western yellow jacket use a synthetic attractant   called n-heptyl butyrate to lure workers into a trap from which they cannot   escape. Fruit juice or various meats can be used as attractants but are not   as effective. Traps can provide some temporary relief for picnics, etc., by   drawing workers away from people, but they are not effective for area-wide nest   control even though many yellow jacket workers may be trapped. Early season   trapping may catch queens, which can reduce the number of nests in the area   later in the year.


The principle behind this practice is the denial of attractive food to the   foraging worker wasps. If begun early in the summer and carried out through   mid-autumn, proper sanitation will help to reduce the buildup of foraging yellow   jackets in an area. Trash containers should be kept closed whenever possible.   Other sources of sugar or protein need to be enclosed or removed.

Interesting Facts

Recent surveys indicate that between 0.5 and 1.0 percent of the population   may be allergic to yellow jacket venom.

Sources: PNW 2003 Insect Management Handbook, Virginia Cooperative Extension   Publication 444-265.

April 23, 2003