Tetramorium caespitum (Linnaeus)
The pavement ant is an introduced species and is one of the most commonly encountered house-infesting ants in Pennsylvania. The ants were likely carried to the United States in the holds of merchant vessels during the 1700s to 1800s. These ships were filled with soil from Europe to provide ballast on the trip to the States. Once in port, the soil was removed, and goods were loaded on the ships to carry back across the Atlantic.
The pavement ant is a soil-nesting species that currently has a distribution from New England to the Midwest, and south through the Mid-Atlantic States to Tennessee. It is also found in parts of California and Washington.
Description and Behavior
The pavement ant workers are about 2.5–4 mm long and vary in color from dark brown to black, with parallel furrows or lines on the head and thorax. The pedicel, which connects the thorax and abdomen, has two segments. The posterior/dorsal thorax has two spines that project upward to the rear, and they carry a stinger in the last abdominal segment.
The swarmers or reproductive ants are winged, about twice the size of the workers, and also have a furrowed head and thorax. The spines are evident on the females but absent on the males.
Pavement ant worker
Very little information is available on pavement ant colony biology. Most information is gleaned from the observations of ant behavior aboveground.
Winged reproductive ants typically swarm in the spring but have been known to emerge any time of the year in heated structures. It is not uncommon to see swarming in late fall and into February even in colder climates.
After emergence, the ants mate and the queens burrow into the soil to begin laying eggs. Worker ants develop over a two-to-three-month period.
Most colonies are located under sidewalks, building slabs, and large rocks. Ants enter buildings through cracks in foundation walls and interior slabs. It is common to see sand piles and small soil particles in structures near cracks in concrete slabs or at the top of foundation walls where the ants deposit debris from excavated nests. Similar piles are seen in the warmer months at the cracks in sidewalks.
Pavement ants feed on a wide variety of food. Sweets, including sugar, nectar, fruits, and syrups are readily taken. Grease, dead insects, and small seeds also are collected and stored in the nest. Nearly any morsel of food that falls to the floor will be consumed.
Control of foraging pavement ant workers can be accomplished through the use of baits. The workers carry the baited material back to the nest, eliminating the colony. Many different types of bait are available to the homeowner in this regard. However, baits containing hydramethylnon, fipronil or boric acid are slower acting and do not kill the workers before they have had a chance to share the baits with the queen and developing immature ants. Place the baits in areas where ant activity has been observed and make certain that children or pets cannot reach them. Maintain sufficient amount of baits to satisfy the colony by replacing used baits. It may require two weeks or longer to obtain control.
Pesticides are poisonous. Read and follow directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams, or ponds.
Authored by: Steve Jacobs, Sr. Extension Associate
February 2000 Reviewed January 2013
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