Thief Ant


Actual Size: 1.5 to 2.2 mm

Characteristics: Brown to yellow in color

Legs: 6

Antennae: Yes

Wings: No

Habitat: Nests are found in exposed soil, under rocks, or in rotting wood. Indoors, nests can be found in woodwork and masonry.


  • Prefer foods with higher protein and fat content.
  • Will nest near other ants, then steal the food and larvae from their neighbor.
  • Since they feed on dead rodents and insects, they can contaminate pantry products as they forage.

Thief Ants in the North and East Bay of California

Thief ants are little bandits that nest near other, larger ants. They are named for their habit of entering their neighbor’s nest, then stealing their food, and preying upon their larvae. Common in the North and East Bay of California, their nests are connected to the nests they rob by tunnels that are too small for other ant species to access, but big enough for the tiny worker thief ants to move through. Omnivores, thief ants feed on both plants and animals, eating rodents, insects, potato chips, and other greasy foods. They invade homes through cracks and crevices contaminating stored pantry products and packaged food items.

Thief Ant Habitat

Outdoors, thief ant nests are located in exposed soil, under rocks, or in rotting wood. They invade homes from the outdoors, generally during hot weather nesting in cracks, crevices, and wall voids. Thief ants utilize electrical wiring in wall voids to move from room to room. When invading homes, they can be found in cabinet voids, under countertops, and behind baseboards.  They eat a variety of household foods such as meats, bread, sweets, nuts, animal fats, vegetable oil, and dairy products. Due to their small size thief ants can easily enter packaged food that would be inaccessible to larger ants. Thief ants are commonly found in kitchen and food prep areas of homes and businesses.

Thief Ant Behaviors, Threats or Dangers

Although thief ants rarely bite, they are known to feed on dead and decaying animals, allowing them to introduce pathogens into your home that can cause fevers, diarrhea, and vomiting. When foraging through kitchens and pantries, they leave behind disease-producing organisms, transmitting bacteria onto human food. Thief ants trail inside cabinets, on walls, baseboards, tree branches, and shrubs. Due to their small size, they are able to forage into packaged foods. If a thief ant infestation is suspected, it is recommended to contact a licensed ant exterminator.