INTRODUCTION
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.
RECOGNITION
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.
SIMILAR GROUPS
- Pharaoh ants (Monomorium pharaonis) have 12-segmented antenna with
3-segmented club.
- Big-headed (Pheidole megacephala) and fire (Solenopsis spp.) ants
have thorax with 1 pair of spines on upper surface.
- Other small pale ants with 1 -segmented pedicel.
BIOLOGY
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).
HABITS
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.
