Yellowjacket wasps (often mistakenly identified as "bees") may become a nuisance around buildings. From August through October, when yellowjackets have built up large populations, they seek food such as carbonated beverages, cider, juices, ripe fruits and vegetables, candy, ice cream, fish, ham, hamburgers, hot dogs at picnics and other outdoor events. Many are attracted in large numbers to garbage cans. Others fly in and out of nests built around buildings and areas where people live, work and play, causing fear and alarm. Although yellowjackets are considered quite beneficial to agriculture since they feed on harmful flies and caterpillars, it is their aggressiveness and painful stinging ability that cause most concern. Nevertheless, unless the threat of stings and nest location present a hazard, it may be best to wait for freezing temperatures in late November and December, to kill off the colony. Stinging workers do not survive the winter and the same nest is not reused.
The German yellowjacket is distributed throughout the northeastern quarter of the United States and often nests in wall voids and other cavities. (Other yellowjackets usually nest in the ground.) Nests in attics and wall voids are large and workers can chew through ceilings and walls into adjacent rooms. The nest of the German yellowjacket is made of strong light gray paper. Colonies of the German yellowjacket may be active in protected wall voids into November and December when outside temperatures are not severe.
Problems with yellowjackets occur mainly when:
Yellowjackets are sometimes responsible for an infection following a sting. A contaminated stinger can inject the bacteria beneath the victim's skin. Blood poisoning should be kept in mind when yellowjacket stings are encountered.
Sting victims often can identify the location of yellowjacket nests. Soil nests are often located under shrubs, logs, piles of rocks and other protected sites. Entrance holes sometimes have bare earth around them. Entrance holes in structures are usually marked by fast-flying workers entering and leaving. A nest high in a tree should not be a problem unless it is where it may be disturbed. Be sure to wear a bee suit or tape trouser cuffs tight to shoes.
Habitat and Harborage Reduction
Management of outdoor food sources is very important.
When possible, treat after dark; workers are in the nest at that time. If nests are located high in a structure where there may be a danger from falls or electrical wires; maintenance staff who also do pest control may be wise to hire a professional pest control contractor to treat the nest.
Begin with the entrance hole in view and a good plan in mind.
Application to Underground Nests
Application to Wall Voids
Control of yellowjackets with traps has not been effective with eastern species. Spraying trash cans and the outside of food stands will reduce or repel yellowjackets at sporting events; the treatment will not last long. Remember, do not contaminate food surfaces.
Ongoing monitoring throughout the active yellowjacket season is essential when a pest management program is in place at locations where there are outdoor activities. Whenever possible, screens should be installed in school room windows and garbage cans should have tightly-sealing lids.
September 17-18, 2019
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October 30, 2019
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October 15-18, 2019
San Diego, CA
December 4-6, 2019
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