Some individuals have a severe or life-threatening allergic reaction to the venom released during a sting, so it's important to address yellowjacket populations that the public may come in contact with. Their populations don't reach large numbers until later in the summer, but it's during the spring when the queen goes in search of a nesting site. Depending on the species of yellowjacket, nests can be established in the ground, in trees, under the eaves of a building, in wall voids, and in the hollow spaces of children's play equipment. Now is the time to begin regular inspections and monitoring for the signs of a yellowjacket nest and continue monitoring until after the first frost.
In general, yellowjackets are roughly ½ to 1 inch in length with smooth looking bodies that are black with bright yellow or white markings on the abdomen depending on the species. These social insects live in colonies with thousands of individuals. Their seasonal nests are made of a papery material, which may not be visible if the nest is in the ground. Aerial nests are large and globular in shape with only one entrance and exit. Paper wasps also form papery nests under eaves or window ledges, but they are the shape of an inverted umbrella with individual cells pointing downward. Paper wasps can also be aggressive, although not to the extent of yellowjackets. Yellowjackets are especially a nuisance to humans because they scavenge in trash containers, on food and beverages eaten outside, and on ripe fruits and vegetables found in gardens and on trees.
Although yellowjackets can be a pest to humans they are beneficial to have in the natural environment. They are predators and feed on other unwanted insects such as caterpillars. If a yellowjacket nest is discovered but isn't bothering anyone or causing a potential hazard, it can be ignored. If the nest is in an area where people are in danger of being stung, use integrated pest management (IPM) methods to address the problem.
- Begin looking for nests early in the season on sunny, warm days. Weekly inspections of the building, grounds and play equipment can make managing a yellowjacket population much easier. Report any suspicions or visible nests to the pest management professional, facility manager, director, landlord or to whomever is in charge of pest control at your child care facility.
- Keep trash cans, dumpsters and recycling containers away from doorways and other high traffic areas used by staff and the children.
- Make sure trash cans and dumpsters have tight fitting lids or have self-closing lids. Use heavy gage plastic trash bags inside garbage cans.
- Empty trash and recycling containers regularly. Wash and rinse out the container frequently, especially when food and beverages spill in the can or on the lid.
- If you're serving beverages outside, serve them in covered cups with straws to keep yellowjackets from entering the cup and stinging the children in the mouth when they drink. Do not leave open soda cans or other beverages outside and then drink from them.
- Make sure window and door screens are in good shape. Place screening over ventilation openings to prevent yellowjackets and other insects from entering the building.
- After checking for nests, seal openings in children's play equipment when possible.
- If needed, traps can be used to temporarily reduce the number of yellowjackets in sensitive areas. Food based attractants tend to be more successful than pheromone traps when dealing with yellowjackets.
Because of the aggressive nature of yellowjackets, professional assistance is recommended for nest removal. If you are outside and yellowjackets are bothering you, don't squash them. Many species will emit a chemical that alerts other yellowjackets to attack. Attached are two fact sheets about yellowjackets and ideas for controlling them.