Nests remain active until September and October. The easiest time to control yellowjackets is in the spring and early summer while the colonies are still small. Baiting worker yellowjackets can be done by using commercially available containers with Knox-Out 2FM pesticide. The pesticide is mixed with canned mackerel or other bait such as fish based cat food. The bait containers are then hung from a tree limb or other support at least 5 feet above the ground to prevent access by children or pets.
Workers carry the pesticide back to the nest and can eliminate the entire colony.
Trapping yellowjackets is an alternative measure that does not require the use of pesticides. Trapping becomes more effective later in the summer, when yellowjacket workers start aggressively searching for sweets and protein. Yellowjacket traps are available in grocery and hardware stores, or you can make your own. Check foods and soda cans before putting them in your mouth. Localized swelling and pain are typical reaction to the sting by a wasp or bee and they gradually disappear within a few hours.