Thief Ant Solenopsis molesta
One of the smallest ants found infesting buildings, measuring less than
1/16-inch in length.
Thief ants derive their name from their habit of locating their colonies
close to those of other ants to steal that ant's food and even capture and eat the other ant's eggs and larvae.
Colonies are usually small and are difficult to find. In homes, trails are often seen in bathrooms and kitchens and
in and around windows where the ants can find moisture and food.
This ant will nest in soil, in wood, in voids, and in just about any
suitable location. Finding the nests is extremely difficult.
Thief ants can be difficult to control. Often they are mistaken for Pharaoh
ants; unfortunately, the baits used to control that ant may not be effective for thief ants. Thief ants tend to
prefer foods with higher protein and fat content. The experience of a professional with access to a number of
different ant baits is likely to achieve better results.
The Thief ant gets its name
from its habit of stealing food and brood from other ant nests, and on occasion has been known to take over the
As with most indoor pests, good sanitation practices will make your home less attractive to ants. Always clean up
food sources such as spills, pet food or garbage. Store food in containers. Use a sponge and soapy water to kill
ants seen on counters, cabinets, etc. Cut back tree branches or bushes that come in contact with exterior walls.
Make sure to seal any cracks or gaps in foundations or walls with caulk.
Feeds on immature forms of other ants and insects. Also attracted to greasy
or high-protein foods, such as cheese and animal matter.
Queens lay an average of 105 eggs, which incubate for 16 to 28 days. Larval
stage may last 21 days in summer, but can last throughout the winter.
Also known as grease ants and sometimes “sugar ants”, thief ants are one of
the tiniest household ant species found worldwide. These ants are about 1/16-inch long. The name is derived from
the ants’ habit of stealing larvae and pupae from neighboring colonies. They are omnivorous and feed on food that
is high in protein, including the larvae and pupae of other ant species, as well as other insects.
While thief ants and pharaoh ants resemble one another, several
characteristics of the thief ant can ensure proper identification. The thief ant is light brown or yellow in color
and measures only 1/16-inch in length. Thief ants have petioles with two nodes, one thorax without spines, ten
segmented antennae with two-segment antennal clubs and small, compound eyes. The thief ant also tends to forage in
well-defined trails, while Pharaoh ants are less likely to make trails but do so after food or water sources have
Thief ant colonies tend to be smaller than those of other species, but can
contain two or more queens and several thousand workers. The thief ant queen is capable of establishing new
colonies without the help of her workers, though she may still choose to include two or more workers after
Thief ants feed on protein and greasy foods such as nuts, meats, cheese,
peanut butter and sweets. Because worker thief ants are small enough to enter food packaging, they can become a
nuisance in the kitchen. Outside, thief ants forage for dead insects and rodents. Because of this, it is possible
they can transmit pathogens from a food source to human food.
Thief ant mating swarms appear from July to September, though these
reproductive ants may also be seen indoors in the summer. When thief ants enter homes and buildings, they form
trails from the food source to their nests.
Thief ants nest in rotting wood and soil. They may also nest indoors in
small spaces, including wall crevices, cabinet voids, under countertops and behind baseboards. Because thief ants
nest in hidden areas, their nests are difficult to locate. The best way to address a thief ant infection is to
contact your local pest control professional.