Field Ants Identification Guide
Quick Facts About Field Ants
Field ants are medium-sized ants that build mounds in lawns, fields, and along sidewalks. They’re mostly an outdoor ant, but they’re often mistaken for carpenter ants when they wander inside.- Size: About 1/8 to 3/8 inch
- Color: Black, brown, red, or two-toned, depending on species
- Body: One node and an uneven back when viewed from the side
- Nests: Soil mounds in lawns and open areas, sometimes against foundations
- Behavior: Can bite and spray formic acid when their mound is disturbed
- Diet: Honeydew, sweets, and other insects
Field Ants vs. Carpenter Ants
This is the most common mix-up with field ants.- Back profile: Carpenter ants have a smooth, evenly curved back. Field ants have an uneven back with a dip.
- Nests: Field ants nest in soil mounds. Carpenter ants nest in wood.
- Signs: Carpenter ants leave sawdust piles; field ants leave soil mounds.
See our carpenter ant guide.
Signs and Where They Nest
- Lawn mounds: Mounds of soil in sunny lawns, sometimes large
- Along foundations: Nests against walkways, patios, and the house
- Occasional indoor ants: Foragers wandering inside, or swarmers in spring and summer
Health & Property Risks
Field ants can bite and spray formic acid, which stings a bit, but they aren’t dangerous. Large mounds can damage turf and make mowing difficult.
Do Field Ants Need to Be Treated?
Mounds away from the house can usually be left alone. Treat mounds near the foundation, walkways, or play areas, or if ants are coming indoors. Baits and mound treatments work well, and if you’re not sure whether they’re field ants or carpenter ants, have them identified. See our ant control services.
Frequently Asked Questions
What are the ant mounds in my lawn?
They’re often field ants, which build soil mounds in sunny lawns and open areas. In parts of Tennessee, fire ants build mounds too, so check whether the ants swarm and sting.
How do I tell field ants from carpenter ants?
Carpenter ants have a smoothly curved back and nest in wood. Field ants have an uneven back and nest in soil.
Do field ants bite?
They can bite and spray formic acid, which stings a little, but they aren’t dangerous.
Do field ants come in the house?
Occasionally, as foragers or swarmers, but they’re mainly outdoor ants.
Should I treat field ant mounds?
Only if they’re near the house, walkways, or play areas, or if ants are coming inside.
