The thief ant takes its name from their habit of nesting close to, and in some cases inside the nests of other ants, from which they steal food. They are quite common in the Greater Kansas City area.
The length of the thief ant is around 1/16” or very slightly larger. Their color also varies from yellow to bronze to dark brown with a shiny appearance. The petiole consists of two segments. The antennae contain 10 segments terminating in a 2-segmented club. They also have a stinger.
Due to their variability in size and color the thief ant is sometimes mistaken for the pharaoh ant. The pharaoh ant can be similar in size and color. The pharaoh ant is 1/16 inch long and light yellow to red. However, the pharaoh ant’s abdomen has black markings and the hind portion is usually somewhat darker. Further, more the antennae of the pharaoh ant have 12 segments with a 3-segmented club.
Colonies of thief ants are generally small varying from a few hundred to several thousand workers and a multitude of queens. Swarmers take flight and mate from June until late fall. The developmental time from egg to adult takes around 50 days to several months.
Thief ant colonies are found both indoor and outdoors in the Kansas City area. Nests are large and often have tiny tunnels connecting to the nearby nests of larger ants from which they habitually steal food and brood. Outside they can be located under rocks, around walkways and house foundations, in rotting wood and exposed soil. Indoor nests are found in any small crevices, particularly woodwork and masonry, under floors and behind baseboards.
These ants are prevalent in households, in which they forage for foods with high protein content such as grease, cheese, meat and seeds for the oil content. It is important to note that due to their small size, they can easily enter packaged foods and medical supplies, as do Pharaoh ants. They also feed on immature forms of other ants and scavenge on dead insects and rodents. Unlike most other ants they do not appear to feed on sweets. They travel great distances in search of food, and once a source is located they form a trail from the food to the nest moving in columns of ants.
The thief ant is native to the United States and is readily found here in Kansas City, as well as much of the country east of here.
The thief ant is difficult to control. Indoor nests are best treated by baiting. Baiting can be enhanced by placing it in conjunction with something of an oily content, such as vegetable oil or peanut butter. Non-repellent pesticidal dusts, liquids or granules can also be used, but should not be placed in near proximity to the baits. In the case of outdoor colonies, the most prompt strategy involves direct treatment of the nest site. Colonies may be located by inspection of foraging trails.