Yellow Jackets, Vespula, Avispa

Life History

Yellowjackets are social wasps living in colonies containing workers, queens and males. Colonies are annual with only inseminated queens overwintering. Fertilized queens occur in protected places as hollow logs, in stumps, under bark, in leaf litter, in soil cavities and human-made structures. Queens emerge during the warm days of late February to early April, select a nest site and build a small paper nest in which eggs are laid. After eggs hatch from the 30 to 50 brood cells, the queen feeds the young larvae for about 18 to 20 days. Larvae pupate, emerging later as small, infertile females called workers.

When queens first emerge from overwintering they are very actively foraging for food. This is an excellent time to set out apple juice traps (March, April, and May). During this period, for every queen that is trapped and killed, it means that there will be five hundred to five thousand fewer Yellow Jackets workers in the area!!

After the queen establishes a nest and she has had many workers, she no longer forages for food. Instead it is the workers that search out and bring back food to the ever growing colony of larvae and young Yellow Jackets. This occurs late April through September. As you are well aware, the workers are ubiquitous, crawling over food threatening guests, and innocent picknickers. They have no sense of humor, thus some of us feel that they have no place at a barbecue. So trap, trap and trap as many Yellow Jackets as you possibly can. Their numbers are excessively high due to accumulation of human garbage. For every Yellow Jacket worker that is eradicated, there will be 20 less wasps later!! The larvae will receive less food thus hampering growth of the colony. By the way, watch that soft drink you were sipping on and set down briefly. Some people have been stung in the throat!

During October, it is again an excellent time to eradicate queens. As the weather cools in October and early November, the new virgin queens emerge and mate with the drones. The newly mated queens then search for an appropriate place to spend the winter. All this frantic mating and searching requires considerable energy. To get that energy the queens become voracious feeders on sweets. At that time it is good to set out apple juice traps and pheromone traps. Pheromones are natural chemicals produced by wasps which attract other wasps. Again, for every queen trapped at this time means one thousand to five thousand fewer wasps during the next season.

Remember, no matter how successful we may be in trapping Yellow Jackets, we cannot eliminate them all. We can however, bring their numbers down to tolerable levels.

Venom and Stings

Most home remidies for Yellow Jacket stings simply do not work. What is needed are chemicals that are safe to use and are specific in their effect on the wasp venom.

Remember that when wasps sting, they can control the amount of venom that is injected, therefore not all stings are alike. I have experienced this personally. Once I was stung by threee wasps about the same time. Two of the stings itched for a while, but soon went away. The third sting was somewhat painful but within a two day period it was gone.

So we have two variables going, one is the amount of venom injected by the wasp and secondly the sensitivity of the person being stung. (Yellow Jackets are a type of wasp) About one in a thousand people are hyperallergic and must have injections immediately after being stung. If not treated, 66% of hyperallergic people die within an hour and 96% die within five hours due to respiratory obstruction and anaphylactic shock.

Pain by stings of wasps is due to the effect of biogenic amines that include histamines. What is needed to counteract the pain and effect of these histamines, are antihistamines. The best procedure is to wash the area stung with soap and water, then apply an antihistamine preparation. Antihistamine sprays are also available. There are antihistamines available (non-prescription such as benadryl) that can be taken orally, but one must not drive or work power equipment after taking benadryl because it will make a person very sleepy. In any case, if a person is stung in the mouth, it is essential and urgent that they are taken immedialely to a hospital emergency room, (allergic or not) because the tongue and throat can swell to an extent that makes breating and eating difficult if not impossible. It may only take 3 to 5 minutes after being stung for a person to die if they cannot breath. In the United States, approximately 50% of all people who die from bites of venomous animals (wasps, snakes, spiders, etc) succumb to wasp stings!

The most likely place where stings occur are near the entrance of wasp nests. Stpping on the entrance of a Yellow Jacket nest is a sure invitation for a mass attack by hoards of wasps.

For details on Yellow Jacket Life History see

Ohio State Yellow Jacket Web Site

Avispa, Universidad Pablo de Olavide