Pavement Ant

Order/Family: Hymenoptera/Formicidae

Scientific Name: Tetramorium caespitum (Linnaeus)

Description: Pavement ants are 1/16- to 1/8-inch long with a dark body and lighter colored legs. They have two small spines on the back portion of the thorax, two nodes in their petioles, and their bodies are covered with stiff hairs. Pavement ants are easily identified by the narrow, parallel grooves on their heads and thoraxes.

Biology: Little is known about the biology of this species. The developmental time (egg to adult) is 36 to 63 days. Indoors, swarmers emerge anytime, and they emerge outdoors in June and July.

Habits: Pavement ants are commonly found in metropolitan areas in the eastern and central United States and in California. They nest outdoors under flat stones, under sidewalks, along curbing, under concrete slabs, etc. They invade structures in search of food and are a particular problem in areas where slab-on-grade construction is prevalent. Inside structures, they nest in walls, insulation, floors, and near heat sources during the winter.

Pavement ants feed on insects, meats, seed, and sweets, but they prefer meats and greases. They are slow-moving insects and are frequently observed in areas where they are prevalent. They forage in trails as far as 30 feet from the nest. Although they are not particularly aggressive, workers can bite and sting.

Control: All cracks and gaps in exterior walls which provide access to voids or interior areas should be sealed. Cracks in slabs and gaps in expansion joints should be filled. All debris from the exterior of the structure and other items on the ground where these ants nest should be removed.

Pavement ants are attracted to and feed on sweet and protein-based baits. Baits should be placed where ant trails have been established and in locations where the ants have been sited. Unless using containerized baits indoors, baits should be placed so they are inaccessible to children and pets. The baits should be checked often for feeding activity and availability.Sweet baits are the most effective, but if acceptance is low, a protein bait should be considered. 

The most effective control is to follow ant trails to the nests and treat them with a residual insecticide.  Particular attention should be paid to cracks and expansion joints in slabs, driveways, sidewalks, etc. Metal extension tubes should be used to inject liquid products directly into these sites. If subslabs areas require treatment, the use of foam injection or liquid subslab treatment should be considered. Nests in wall voids are more easily treated by aerosol injection or application of a dust formulation. When the nests can not be located, a barrier spray using a microencapsulated or wettable powder formulation should be applied to foundations and the soil immediately adjacent to the building. This is effective in repelling foraging workers and preventing them from reentering the structure.

Copyright © 2001 [Alan Luke]. All rights reserved.
Revised: 06/25/10. Home