Yellow jackets (Dolichovespula spp., Vespula spp.) , black wasps with jagged yellow markers, are considered beneficial because they feed on large numbers of pest infestation. Nevertheless, many people view yellow jackets as pests themselves, because they can deliver wicked stings when hardened. Although yellow jackets typically prefer nesting in quiet, out-of-the-way places, some colonies develop in areas that experience a lot of human action. Those nests will need to be eradicated to avoid painful and potentially dangerous stings. The ideal chemical for the job depends on whether you’re dealing with a curved aerial nest or a single unseen beneath the ground.
A few yellow jacket queens build exposed nests that hang out in the open from tree limbs, shrub branches or roof eaves. The University of Idaho Extension recommends treating aerial nests using a pyrethroid-based insecticide. Pyrethroids quickly kill yellow jackets but only have reduced toxicity for people, birds and pets. The common names of pyrethroids always end in “-ate” or “-thrin,” like “cypermethrin” or “lambda cyhalothrin,” both widely used to eliminate the stinging pests. To treat the nest from a safe distance, then pick a pyrethroid product that comes at a ready-to-use aerosol format using a jet propelled trigger that sprays a stream of insecticide at least 20 feet away. Take the pesticide right into the entrance, typically located at the bottom of the nest, and then completely soak the outside of the nest as well. Wait at least 24 hours before returning to the treatment site in order to check for yellow jacket activity. Repeat the spray treatment every 3 days until you no more spot live yellow jackets in the nest area.
Ground-dwelling yellow jackets are somewhat more challenging to control than people residing in aerial nests because they are often located in hard-to-find abandoned rodent burrows and other cavities that are protected. Carbaryl-based dust pesticides effectively control subterranean yellow jacket populations, but you have to get the dust inside the nest in order for it to work. As soon as you find the nest entrance, wait until dusk, and until you do not see yellow coat action, to sprinkle carbaryl dust around the entrance hole. Then use a hand duster or a moist liquid detergent bottle half filled with the insecticide product to get several puffs of their dust inside the opening. Instantly leave the treatment area, and don’t return for at least 24 hours. Duplicate the dusting process about every 3 days for as long as you visit yellow coat activity at the nest area. Once you successfully remove the stinging insects, seal the entrance hole with soil treated with carbaryl dust or a pyrethroid-based aerosol insecticide. This should maintain any surviving yellow jackets from reestablishing a colony.
Timing Chemical Treatments
Mid- to late spring is the ideal time to chemically treat a yellow jacket nest because the queen has started establishing her perverse but its numbers are still quite small. If you find a curved airborne nest earlier in the season, only knock it down with a powerful blast of water from a garden hose. Apply chemical therapies in dusk or after dark when cold night temperatures arrive and the majority of the foragers are calmly resting from the nest. Yellow jackets are sluggish and also have trouble flying as soon as the temperature falls below 50 degrees Fahrenheit.
Yellow jackets attack as soon as they sense their nest being threatened by poison. Protect yourself from both stings and compound exposure by wearing heavy clothes, goggles, thick work gloves, socks and shoes, a hat, and a face mask or bee veil. Wear a long-sleeved shirt and pants, taping the cloth around your ankles and wrists to keep the agitated insects from getting beneath your clothes. Light may startle yellow jackets into aggressiveness, so avoid shining a light source straight at a nest opening. If you have to use a torch, cover it with red cellophane because the insects can’t see red light. Never, ever try to deal with a nest if you’re allergic to yellow jacket venom. Enlist the assistance of a non-allergic individual or a professional exterminator rather.