Yellowjackets' persistent presence is an annoyance, sometimes a stinging memory, at sporting events, picnics and other traditional fall outdoor activities.

Huge numbers of yellowjackets start foraging for food for developing queens and other members as the colony nears maturity. Since their usual diet of caterpillars is becoming scarce, yellowjackets scavenge for other sources of nutrition, notably sweets such as soft drinks, fruits, ice cream and beer. Yellowjackets also like popular picnic items such as chicken and ham.

"Yellowjackets are considered one of the most dangerous stinging insects in the U.S. because they tend to be unpredictable and often will sting if their nests are disturbed," said Mike Potter, Extension entomologist with the University of Kentucky College of Agriculture.

"The best way to reduce the threat from yellowjackets is to minimize foods that attract them," Potter added. "When eating outdoors, keep foods and beverages covered until you're ready to eat. Yellowjackets will fly into a soft drink or beer in search of food, so always check cans or cups that have been left standing before taking a swallow.

"Clean up spills as soon as possible and put leftovers away when you've finished eating.

Dispose of trash promptly, preferably in a container with a tight-fitting lid or by using double plastic bags closed securely. It's best to put trash cans and dumpsters away from picnic tables or other areas where people are gathering."

People with home orchards and gardens should collect and discard overripe or

decomposing fruits or vegetables that might be attractive to foraging yellowjackets. Otherwise, it increases the number of yellowjackets in an area and the chance of someone being stung, according to Lee Townsend, Extension entomologist.

"To help repel yellowjackets, sponge outdoor tables and food preparation areas with a diluted solution of household ammonia and water, using about six ounces of ammonia per gallon of water. Also spray this solution in and around trash cans to discourage yellowjackets. Be sure to use household ammonia, not bleach," Potter said.

"Try to avoid yellowjackets," he added. "When they're foraging for food away from their nests, yellowjackets usually aren't aggressive and will not sting unless provoked. So avoid the temptation to 'swat' at them. Instead, just move away carefully."

Although some people mistake them for bees, yellowjackets' behavior and food preferences distinguish them from bees, according to Potter.

"Yellowjackets are more aggravating than honeybees and bumblebees," he explained. "They habitually scavenge at outdoor food locations like picnics, outdoor restaurants, and trash cans or dumpsters. The bees gather around flowers to find pollen and nectar."

Since some people are very allergic to the venom from a yellowjacket, wasp or hornet sting, Potter said they should see a doctor immediately if allergic symptoms such as hives, difficulty breathing or swallowing, or wheezing develop.