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Harmless

Pavement ant

Tetramorium immigrans
Also called Tetramorium caespitum (older name)

Pavement ants have a tiny stinger but rarely use it on people, and they are a kitchen nuisance rather than a danger.

Pavement ant, photo 1
Photo: Jake Nitta, CC BY 4.0, via iNaturalist
SizeAbout 2.5–4 mm (about 1/8 inch) for workers; winged ants about twice that
Where in the houseKitchen, basement, garage, outside near the house
WhenMost often seen spring and summer, with swarms peaking around June and July; in heated homes, workers and winged ants can show up indoors in late fall and winter.

Check these features

  1. Small dark brown to blackish ant, often with lighter legs and antennae
  2. Fine parallel grooves on the head and thorax, visible with a magnifier
  3. A pair of tiny spines on the back of the thorax
  4. Two bumps (nodes) in the waist
  5. Little piles of sand or soil along sidewalk cracks, slab cracks or the top of basement walls

Bites and stings

Rarely stings people. A sting, if it happens, is a minor prick that fades quickly; wash the spot with soap and water.

What to do

  1. Wipe up the ant trail and the food it leads to with a soapy sponge or cloth.
  2. Store food in sealed containers and clean up crumbs, grease and pet food.
  3. Place bait stations where ants are active, keep them filled, and follow the label; it can take two weeks or more.
  4. Look for sand piles at slab and foundation cracks to find where they enter, and seal those cracks.
  5. If ants keep returning, ask a licensed pro about treating the nest outside.

Look-alikes

Odorous house antOdorous house ants have a single hidden waist node, no spines, a smooth look, and a rotten-coconut smell when crushed.
Red imported fire antFire ants are reddish, come in mixed sizes in the same colony, build loose dirt mounds in lawns, and swarm out to sting when disturbed.

Why it came inside

Colonies live under sidewalks, driveways, patios and house slabs, and workers come up through cracks in the slab or foundation to collect sweets, grease, crumbs and pet food. In heated buildings winged ants can come out of the slab in any season.

Keep it out

  • Seal cracks in foundations, slabs and around doors with caulk or sealant.
  • Keep floors and counters free of crumbs and grease, and do not leave pet food out.
  • Keep vegetation trimmed back from the house.
  • Keep garbage in lidded containers.

What helps

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Bait stations

Enclosed baits work slowly as insects carry the bait back to where they hide. Don't spray near the baits, and follow the label.

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Caulk and sealant

Silicone or siliconized acrylic caulk closes cracks around windows, pipes and baseboards. Bigger gaps need foam backer rod or expanding foam first.

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Airtight pantry containers

Glass or thick plastic containers with tight lids keep pantry pests out of flour, cereal, rice and pet food.

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Door sweep

Closes the gap under an exterior door. If you can see daylight under the door, bugs can get in.

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Hand lens

A 10x magnifier makes small features easier to check, like eye patterns, markings or the shield on a tick.

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Sources

  1. University of Florida IFAS (EDIS Featured Creatures)
  2. Washington State University Pestsense
  3. Maine DACF (reprint of Penn State Extension fact sheet)

Checked October 18, 2026. Rating backed by 2 sources. How we rate danger.