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Pest Information

Field Ants

Field Ants

  • Latin Name: Formica sp.
  • Common Name: Field Ants
  • Latin Family Name: Formicidae
  • Other Names: Thatch ant, mound ant, silky ant

Pest Details

Field Ants
Field Ants
Field Ants


Many species in this genus are native to North America, and are found commonly throughout the continent.


These are fairly large, single-node species, with colors ranging from black to brown to reddish, or combinations of these colors. They rarely invade structures, but are common in wooded or grassy areas outdoors. They cannot sting, but they will readily bite to cause a slight opening in the skin, and then spray formic acid onto the bite wound to cause a stinging sensation. Their common names are derived from their habit of creating large above-ground mounds of vegetation with their colony nesting inside. The field ants are particularly fond of sweet materials and will forage for honeydew. However, they also are fierce predators of other insects


The species of Formica are very similar to carpenter ants, with colors and size similar. However, unlike the evenly rounded profile to the top of the thorax on carpenter ants, field ants have a deep depression on the posterior half of the thorax. They have a single, prominent node on the petiole and a circle of hairs around the anal opening. The antennae have 12 segments and the first long segment is usually shorter than the height of the head. There are 3 distinct ocelli forming a triangle on the head between the eyes.

Characteristicts Important to Control:

Control of most ants includes correction of the attractions that drew them to a property, including harborage sites, food sources, and moisture conditions. Elimination of insects that provide protein or honeydew sources reduces ant foraging in an area, very important for this species, and cleanup of unnecessary debris or objects on the soil that provide harborage eliminates nesting. Ant bait products in granular, liquid, or gel formulations can be highly effective if the ants accept the bait. If the visible mounds of this species can be found it can be treated directly with a dust or liquid insecticide.

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