Field Ant


Actual Size: 4 to 8 mm

Characteristics: Large; black, brown, or yellowish to bicolored red and black 

Legs: 6

Antennae: Yes

Habitat: Favors outdoor nests in decayed logs or soil. Nests located in lawns, gardens, fields, and foundations of homes and buildings


  • Feeds exclusively on outdoor food resources.
  • Sometimes referred to as thatching or mound ants.
  • Rarely found indoors, but common around homes and other buildings. 

Field Ants in Illinois and Indiana

Field ants get their name due to their preference of nesting out in the open. In Illinois and Indiana nests can be found in lawns, gardens, fields, and parks. Field ants build large mounds in open areas reaching sizes of three to four feet wide and up to two feet tall. Rarely found indoors, field ants are common around homes and buildings. Most species of field ants cause issues around structures when they nest near masonry walls and concrete sidewalks. 

Field Ant Habitat

Nesting in soil or decayed logs, field ants are sometimes referred to as “thatching” or “mound” ants. Nests are constructed from small twigs, grass stems, leaves, or pine needles. Favorite locations for field ant nests are around shrubs, rocks, trees, sidewalks, fences, and foundations of structures. Unlike many ant pest species, these ants do not come indoors for food. They feed exclusively on outdoor food resources, such as live and dead insects and the honeydew produced by aphids. 

Field Ant Behaviors, Threats, or Dangers

Field ants do not sting but will bite if disturbed. If nests are disturbed or stood upon, ants may aggressively swarm out of the nest and bite the intruder. Their bite is typically painful, with some species spraying formic acid into the wound, which stings. While painful at first, the sensation will subside, without any long-term consequences. The large mounds that field ants build can ruin the look of lawns, making lawn mowing difficult, and interfering with the growth of garden plants and woody ornamentals. If a field ant infestation is suspected, it is best to consult a professional ant exterminator.