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Pavement Ant
Order/Family: Hymenoptera/Formicidae
Scientific Name: Tetramorium caespitum (Linnaeus)
Description:
Pavement ants are 1/16- to 1/8-inch long with a dark body and lighter colored
legs. They have two small spines on the back portion of the thorax, two nodes in
their petioles, and their bodies are covered with stiff hairs. Pavement ants are
easily identified by the narrow, parallel grooves on their heads and thoraxes.
Biology: Little is known about the biology of this species. The
developmental time (egg to adult) is 36 to 63 days. Indoors, swarmers emerge
anytime, and they emerge outdoors in June and July.
Habits:
Pavement ants are commonly found in metropolitan areas in the eastern and
central United States and in California. They nest outdoors under flat stones,
under sidewalks, along curbing, under concrete slabs, etc. They invade
structures in search of food and are a particular problem in areas where
slab-on-grade construction is prevalent. Inside structures, they nest in walls,
insulation, floors, and near heat sources during the winter.
Pavement ants feed on insects, meats, seed, and sweets, but they
prefer meats and greases. They are slow-moving insects and are frequently
observed in areas where they are prevalent. They forage in trails as far as 30
feet from the nest. Although they are not particularly aggressive, workers can
bite and sting.
Control:
All cracks and gaps in exterior walls which provide access to voids or interior
areas should be sealed. Cracks in slabs and gaps in expansion joints should be
filled. All debris from the exterior of the structure and other items on the
ground where these ants nest should be removed.
Pavement ants are attracted to and feed on sweet and
protein-based baits. Baits should be placed where ant trails have been
established and in locations where the ants have been sited. Unless using
containerized baits indoors, baits should be placed so they are inaccessible to
children and pets. The baits should be checked often for feeding activity and
availability.Sweet baits are the most effective, but if acceptance is low, a
protein bait should be considered.
The most effective control is to follow ant trails to the nests
and treat them with a residual insecticide.
Particular attention
should be paid to cracks and expansion joints in slabs, driveways, sidewalks,
etc. Metal extension tubes should be used to inject liquid products directly
into these sites. If subslabs areas require treatment, the use of foam injection
or liquid subslab treatment should be considered. Nests in wall voids are more
easily treated by aerosol injection or application of a dust formulation. When
the nests can not be located, a barrier spray using a microencapsulated or
wettable powder formulation should be applied to foundations and the soil
immediately adjacent to the building. This is effective in repelling foraging
workers and preventing them from reentering the structure.
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