Field Ants (Formica) are the most common ants found in Utah’s open landscapes and yards. They are often mistaken for Carpenter ants or Fire ants, but their behavior in the grass is what truly sets them apart.
The ColorsThey come in a variety of shades, ranging from pale brown to reddish-black. Some even have a distinct "two-tone" look with a red head and a black body.
The ProfileUnlike the smooth, rounded back of a Carpenter ant, Field ants have an uneven, "lumpy" thorax with a distinct notch.
SizeThey are medium-sized, typically 1/8 to 1/4 inch long.
Nesting HabitsField ants are famous for building large, low-profile mounds in open, sunny areas. They often incorporate bits of dried grass or small twigs into their mounds to help regulate the temperature.
The Perimeter ScoutThey rarely nest inside homes, but they are frequent "scouts" on the exterior foundation. If they find a way in, they will scavenge for sweets and meats in your kitchen.
The "Bite and Spray"While they don't have a sting, they are known to be "nippy." If disturbed, they will bite with their mandibles and then spray formic acid into the wound, causing a sharp, stinging sensation.
Are these Fire Ants? I saw a red one in my yard.In Northern Utah, we don't have true invasive Fire Ants. If you see a red ant in your grass, it is almost certainly a Field Ant or a Harvester Ant.
Will they kill my grass?The ants themselves don't eat the grass, but their large mounds can smother it, and their tunneling can dry out the roots in localized spots.
Why are there so many in my flower beds?Field ants have a "mutualistic" relationship with aphids. They "farm" the aphids for their sweet honeydew, so if your bushes have aphids, you will have Field ants.
