Pavement ant

📖Overview

Tetramorium immigrans, commonly called the pavement ant, is a small, ground‑nesting ant originally from Eurasia and now widespread in temperate urban and suburban areas worldwide. They build colonies in cracks in pavement, under stones, under building foundations and in lawns. Pavement ants forage widely for sugary and protein foods and are a frequent nuisance pest in homes, restaurants and other buildings.

Colonies vary in size from a few hundred to many thousand workers; some populations form single‑queen (monogyne) colonies, while others can have multiple queens. They are most active in warm months and can be seen forming characteristic trails from nest entrances to food sources on sidewalks and along foundations.

🔍How to identify a pavement ant

Workers are small (about 2.5-4 mm), uniformly brown to dark brown with a slightly darker head and gaster (abdomen). The head and thorax have fine sculpturing (parallel ridges) and the mesosoma (middle section) has two short spines near the rear. The petiole (waist) has two distinct nodes. Antennae have 12 segments with a three‑segmented club. Queens are larger (6-8 mm) and winged or have wing scars if mated.

1. Small workers 2.5-4 mm, uniformly brown to dark brown with a slightly darker gaster.
2. Two petiole nodes (two-segmented waist) and two short spines on the rear of the mesosoma.
3. Head and thorax show fine parallel sculpturing; antennae with 12 segments and a 3-segmented club.
4. Nests in cracks in pavement, along foundations and under stones; look for worker trails at nest entrances.

Lookalikes

↻Life cycle

1. 🥚

   Egg

   Tiny, oval, white eggs laid by the queen; eggs hatch into larvae in about 1-2 weeks depending on temperature and colony nutrition.

2. 🐛

   Larva

   Legless, grub‑like larvae that are fed and cared for by workers. Larval development takes days to weeks depending on resources and temperature.

3. 🫛

   Pupa

   Pupae may be enclosed in a thin cocoon; during this stage the ant transforms into the adult form.

4. 🐝

   Adult

   Workers (sterile females) forage, care for brood and nest; reproductives (winged males and queens) leave for mating flights, after which queens start new colonies or join existing ones.

🍃Diet and predators

🌱Effect on plants and gardens

Pavement ants do not feed on living plants and are not major agricultural pests. They can tend aphids or other sap‑feeding insects, indirectly promoting plant pests in small cases.

How to get rid of pavement ants

Use a combination of sanitation (remove food sources, store food in sealed containers), exclusion (seal cracks and entry points around foundations and windows), and baits (sugar or protein baits with slow‑acting insecticides such as borax or commercial ant baits) placed along trails. For outdoor nests: pouring boiling water into visible nest cracks can kill some workers and queens but may not eliminate large colonies. For heavy or persistent infestations, consider a licensed pest control professional. Avoid spraying random contact insecticides indoors as they can repel workers and cause colonies to relocate.

📍Where and when to find it

Look for worker trails on sidewalks, curbs, driveways and along building foundations; nests in cracks in pavement, under stones, under concrete slabs and in lawns. Inside buildings they appear along baseboards, in kitchens and near food sources.

✨Fun facts

• Pavement ants often create long foraging trails between nest entrances and food sources that can be seen on sidewalks and curbs.
• They commonly nest under pavement and can exploit tiny cracks—hence the common name.
• Pavement ant colonies can be flexible in social structure: some populations have a single queen while others have multiple queens, which affects colony size and behavior.

?Frequently asked questions

📷Photos of the pavement ant