sealPurdue News

October 4, 1996

Take heed when you feed; yellow jackets want your lunch

WEST LAFAYETTE, Ind. -- Unsuspecting picnickers may get a little extra zing -- make that "sting" -- in their sandwich or soft drink right now.

Yellow jackets, those pesky, yellow, bee-like wasps that frequent picnic grounds every fall, are out in force, searching for sweets and proteins, according to Purdue University Extension entomologist Tim Gibb.

Their foraging is why they're often found around trash cans, at picnics and sporting events -- anywhere food is exposed. So folks dining alfresco should take heed before they feed; there may be an uninvited guest already sipping their soda or chomping on their chicken salad.

"Each year in Indiana we receive reports of people being stung in the mouth or the throat area when they inadvertently swallow a yellow jacket that has entered their soft drink can or hidden itself in food about to be consumed," Gibb said. "Stings are always very painful and can be an extremely serious health threat if multiple stings occur or if the victim happens to be hyper-allergic to the venom."

A systemic reaction, or one that causes more than just localized swelling, can be life-threatening, and the victim should go to an emergency room, according to Dr. Donald Clayton, an allergist at Arnett Clinic in Lafayette. He said symptoms include hives, swelling at other parts of the body, difficulty breathing, loss of consciousness, and drop in blood pressure.

"It can accelerate to the point where the person goes into shock," he said.

In the case of multiple stings, Dr. Clayton said, the victim might want to seek urgent care. He explained that nausea, vomiting, lowered blood pressure, and a shock-like state may occur. It's also probably wise to seek medical assistance for stings in the mouth or throat, he said, because swelling could close the victim's airway.

"Just for local swelling at the site of the sting, it's not necessary to see a physician," Dr. Clayton said.

He recommends a cold compress to help reduce swelling and an antihistamine, such as Benadryl, to combat itching.

Avoidance is key to not getting stung, Gibb said. He said it may seem that yellow jackets are everywhere during late summer and early fall because colonies are at maximum size, having started with one impregnated queen in the spring and grown to a population of 1,000 to 4,000 workers. But making food inaccessible to them will encourage them to fly elsewhere, he said.

"Simply keeping foods, including garbage cans, covered and away from people as much as possible will help prevent yellow jacket stings," Gibb said. "This seems like a simple step, but it goes a long way in decreasing the number of stings each year. Increased attention to sanitation will also help."

According to Gibb, keeping garbage receptacles clean, eliminating potential food sources, and keeping doors and windows closed will decrease yellow jacket encounters. And, he said, it's best to stay away from yellow jacket nests.

"Yellow jackets are social insects, which means they live in colonies often containing several thousand wasps," Gibb said. "Like many social insects, yellow jackets can sting, and do so very aggressively when their nest is threatened. When wasps are away from their nests, they're not nearly as aggressive. They must be provoked to sting. Usually stings occur when a wasp is handled or accidentally stepped on or crushed by some unsuspecting person."

Ralph Williams, another Purdue Extension entomologist, said the worker yellow jacket -- an infertile female -- is the one that stings. It injects its venom without leaving its stinger behind, enabling it to sting repeatedly.

Williams said two types of yellow jackets are common in Indiana. The eastern yellow jacket nests in the ground, and the German yellow jacket nests inside structures. Both types of nests can be extensive and house thousands of wasps.

If a nest is found in an area where people might come in contact with it, Gibb and Williams suggest calling an exterminator to deal with it.

"Away from where people might accidentally contact the nest, yellow jackets are beneficial insects," Gibb said. "They feed on other insect pests and also help remove garbage from the environment. For these reasons, nests away from public areas should be left alone."

ACS code/961004 Ag Gibb/9610f8

Sources: Tim Gibb, (765) 494-4570; e-mail,

Ralph Williams, (765) 494-4560; e-mail,

Writer: Andrea McCann, (765) 494-8406; e-mail,

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