Thatching ants

Photo by: Roger Akre
For successful pest management, use IPM (Integrated Pest Management).

Thatching ants are medium to large ants (3/16 5/16 inch long). They can be black to red and black. These ants are sometimes called mound ants because some species construct mounds from plant debris like fir needles. Thatching ants sometimes nest in decayed logs and rarely in wall voids of homes. Their normal pest status comes from nesting in landscapes where physical contact becomes inevitable. When their mounds are disrupted by human contact they bite in mass and then spray the area with formic acid to produce a painful sensation. They are fierce predators and should be protected whenever possible. Mating swarms occur in late summer to early fall.

Management Options

Select Non-chemical Management Options as Your First Choice!!
Revision Date:2/27/2014
Thatching ant nests can go relatively deep in the ground, so nest penetration is quite important and sometimes difficult. Do not apply product to just the nest entry hole as topical applications sometimes incite the remaining ants to simply move their colonies several feet from the surface residue. The entire nest surface and subterranean portion of the nest must be treated. One method is to dig deeply into the nest and stir the contents with a shovel while pouring the recommended amount of pesticide into the nest and surrounding area. Wear protective clothing to avoid bites.

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Pestsense web site created by Becky Hines and Carrie Foss, Urban IPM and Art Antonelli, Extension Entomology, WSU Puyallup
Pesticide information review provided by Catherine Daniels, Washington State Pest Management Resource Service
Database programs developed for Pestsense by Kathleen Duncan and Jim Boyer , Computer Resources, WSU Pullman
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