Chemicals to Kill Hornets in the Ground

Hornet nests are often built where they can be seen.

The most effective chemicals to kill hornets in the ground are synthetic pyrethrins, which are available at do-it-yourself pest control stores. According to Pest Products, ground hornets are often yellow jackets, which are some of the more dangerous of the stinging insects. Yellow jacket nests are often built in walls or underground where they can't be seen. Hornet nests tend to be built where they are visible.

Cypermethrin and Bifenthrin

Sometimes if is difficult to find the hole's entrance where hornets or yellow jackets are nesting. When this is the case, Pest Products recommends a broadcast spray of cypermethrin or bifenthrin through a hose-end-sprayer to areas where the insects have been observed. This action causes the yellow jackets to swarm around the hole's entrance, allowing detection and marking for an insecticide injection. Cypermethrin and bifenthrin are the insecticide's active ingredients. Cypermethrin is sold under many product names, and bifenthrin's trade name is Talstar.

Deltamethrin

Pest Products suggests injecting Delta Dust into the hole once the nest is found. Delta Dust is a water-proof formulation of deltamethrin that provides a better residual control than other products when the colony is moist or wet. Pest Products recommends using a Crusader Duster for the injection; this applicator creates a cloud of dust that moves throughout the hole instead of creating a pile of dust in one location. A Crusader Duster can be purchased at do-it-yourself pest control stores.

Carbaryl

Carbaryl, better known as Sevin, is recommended by the University of Minnesota for ground-dwelling wasps and yellow jacket control. Carbaryl is available in both dust and liquid formulations. The university says the dust is more effective than the liquid because it has a better chance of reaching the nest after injection.

Acephate

Acephate is also recommended by the University of Minnesota for control of ground hornets or yellow jackets. Acephate is widely sold under the trade name Orthene and is available only in a liquid formulation. Because of the type of formulation, it may be the least effective of the listed chemicals if the yellow jacket nest is deep in the ground. If the nest is near the ground surface, however, it is very effective.

References

• Pest Products; Yellowjackets, Yellow Jackets Stinging Insects
• University of Minnesota, University of Wisconsin and Iowa State University; Wasp And Bee Control; Jeffrey Hahn, et al.; 2011