The Thief Ant

Common Name:
Thief Ants
Scientific Name:
Solenopsis molesta (Say)


These ants get their name from their habit of nesting very near or even in the nest of other ants, which they rob of food and brood (larvae and pupae). Recent research indicates that this is most probably a group of species instead of just one species. This is a native species and is found throughout most of the United States


Workers monomorphic, about 1/16" (1.3-1.8 mm) long; queens about 1/4" (6-7 mm) long. Body pale yellowish to light or dark brown in color. Compound eye minute, with 4-6 ommatidium (facets) or less. Antenna 10-segmented, with 2- segmented club. Thorax lacks spines, profile unevenly rounded. Pedicel 2-segmented. Stinger so small that it is rarely used effectively.


  1. Pharaoh ants (Monomorium pharaonis) have 12-segmented antenna with 3-segmented club.

  2. Big-headed (Pheidole megacephala) and fire (Solenopsis spp.) ants have thorax with 1 pair of spines on upper surface.

  3. Other small pale ants with 1 -segmented pedicel.


Colonies are composed of a few hundred to several thousand workers and many queens. Developmental time is 50 days to several months. Flights of swarmers begin in June and end in late fall. A single inseminated female can establish a new colonv. Thief ants have been found feeding on dead rats and mice and, therefore, they might possibly carry disease-inducing organisms to human food. They may also serve as intermediate hosts for the poultry tapeworm, Raillietina tetragona (Molin).


Inside, these ants nest in small crevices, and in woodwork and masonry. They will wander throughout a building in search of food, but forage in trails. They prefer food of high protein content and feed on meats, breads, fruit, animal fats, oils, nuts, and dairy products, but they will readily feed on sweets. They commonly enter structures during hot weather.

Outside, they nest in exposed soil or under objects, in trash, rotten wood, and cavities in trees. Here, they feed on almost anything organic including insects, honeydew (tend plantlice, mealybugs, and scale insects), seeds, and germinating seeds.