Yellowjackets are black-and-yellow social wasps. Hornets and yellowjackets are the most common wasp groups. Hornets usually construct exposed nests in the branches of trees and shrubs or on recessed structures. They also may construct nests in cavities. Most of the yellowjacket species are ground nesting. These are the nests we often discover while on the tractor or lawn mower. However, some nest in buildings or in tree cavities and structural voids. New colonies are started every year by a overwintering mated female yellowjacket. In the spring, the mated female (the new queen) begins constructing a nest in a small hole and laying her eggs inside the cells. New worker yellowjackets help to excavate the nests. By fall, annual nests may contain between 300 and 120,000 developmental cells depending on the species and environmental conditions. In late fall, the workers, males and the old queen die. The newly fertilized females (new queens) find a sheltered place to overwinter. The old nests are not reused. In the South Alabama, perennial colonies have been maintained by some species that are ruled by multiple queens and contain millions of cells.
During later summer and fall, huge numbers of workers are out foraging for food for the newly mated females. Yellowjackets are searching for other sources of nutrition, sweet treats, such as soft drinks, fruits and desserts. The yellow jackets we find hovering around the snack table are foraging yellowjackets. Running into these guys is not as dangerous as disturbing a nest. Our first instinct is to swat at the yellowjackets, but this isn’t the best thing to do. Around the picnic area, sanitation should be the first priority. Use trash cans with tight fitting lids and locate them away from areas where people congregate. Dispose of the trash as it becomes full and change the bag. Keep food and drinks covered until ready to eat. Put food and drinks away as soon as you are finished with them. If fruit trees are nearby, pick up and dispose of any fallen fruit.
Try a dilute solution of ammonia and water (approximately 6 ounces of ammonia per gallon of water). Use household ammonia, not bleach. Spray this mixture around trash cans and use on outdoor eating tables to mask food odors — making the area less attractive to yellowjackets.
Avoid nests if you can. Remember, after the first frost, yellowjackets will die off.
If you are going to try and control yellowjackets, locating the nest entrance is your best bet. Yellowjackets (and hornets) are extremely aggressive when the nest is disturbed. If it looks like a nest may be difficult to access, it is best to call in a professional pest control company. When applying pesticides to the nest, the best time to apply is after dusk when most of the foragers are inside the nest. Try to disturb the nest as little as possible. Again, disturbing the nesting sites often results in aggressive yellowjackets. And, unlike honey bees, yellowjackets are capable of stinging multiple times. Mark the nest during the daytime so you will be able to see it at dusk. While you may use a wasp spray to kill the foragers hovering above the soda cans and watermelons, the nest may be hundreds of feet away. In stores you can find aerosol insecticides for use on yellowjackets. Gently puff the dust at the nest entrance, or thoroughly drench the nest with the liquid insecticide. Please use caution if applying an insecticide to a yellowjacket nest. I recommend gloves, long sleeves, pants and a bee veil. Many are allergic to the sting of the yellowjacket. Sometimes it is best to hire a pest control company or avoid the nest all together if possible.