Acrobat ants (Crematogaster spp.) are native insects that become pests because of their tendency to nest in moist, decaying wood. Many times this decaying wood is in a tree, where the ants can take over chambers of termites and other wood boring caterpillars and beetles. Other nest sites include rotten logs and under rocks and other objects on the ground. Problems arise when the moist decaying wood used as a nesting site is inside a structure, such as one’s home. Acrobat ants that nest outside may forage into houses in search of food and water. There are about 25 species of acrobat ants in the United States, and over 400 species worldwide. One species, Crematogaster ashmeadi, is very abundant in pine forests in the southeastern U.S. In this environment the ant is considered beneficial because it is a major source of food for the endangered red-cockaded woodpecker.
Acrobat ants are so named because when disturbed they frequently run around with their tail ends arched over their heads, giving the effect that they are doing hand stands. They have a heart shaped abdomen (gaster), two nodes on the pedicel between the gaster and the thorax, and two spines on the top side of the thorax. The pedicel is attached to the top part of the gaster, or from a profile view, the pedicel is attached above the midline of the anterior margin of the gaster. Acrobat ants feed on live and dead insects, and frequently tend sucking insects such as aphids, mealybugs, and scale insects for their sugary excretion known as honeydew. When they occur inside houses, acrobat ants readily feed on meats and various sweets.
Compared with other pest ants, acrobat ants are a minimal nuisance to people. But there are times when it is necessary to control them. Best management practices that reduce the chances of structure infestation include pruning trees and shrubs so that they don’t touch the structure, keeping firewood away from the structure, removing dead trees and rotting logs, keeping gutters clear, sealing cracks in the foundation and attic, repairing water leaks, replacing rotten wood in the structure, and keeping food in tightly sealed containers. Common problem areas include skylights, fascia and soffit boards, and woodwork around windows and door frames. Acrobat ants are known to nest in wall voids and certain types of foam insulation. Nests inside structures can be located and treated with an appropriate insecticide formulation such as a liquid spray, dust, or bait gel. Read and follow label instructions for proper application. If the ants are trailing in from outside, the best option is to locate and treat the nest. If the nest can’t be found or reached, applying an appropriate insecticide such as a liquid spray or granular product all along the foraging trail or a bait granular product close to the foraging trail can provide temporary relief while the best management practices described above provide a permanent solution.
For More Information:
Tschinkel, W. R. 2002. The natural history of the arboreal ant, Crematogaster ashmeadi, J Insect Sci (2002) 2 (1): 12.
Hedges, S. A. 2010. Field Guide for the Management of Structure-Infesting Ants, 3rd Ed., G.I.E., Inc., Cleveland, Ohio. 325 pp.
Oi, D.H., and K. M. Vail. 2011. “Ants”. Mallis Handbook Pest Control 10th edition. 11:737-821. D. Moreland (Ed.) Mallis Handbook LLC