Tetramorium caespitum (Linnaeus)
The pavement ant is an introduced species and is one of the most commonly encountered house-infesting ants. The ants were likely carried to the United States in the holds of merchant vessels during the 1700s to 1800s and moved up to Canadian soil from there. The pavement ant is a soil-nesting species.
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: Life History
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.