Workers of this genus measure about 3/8-inch in length.
The color varies depending on the species. Black field ants are more common, but red, brown, red and black, and golden yellow species may also be encountered around homes and buildings.
A group of about a dozen species of ants in the genus Formica are known as field ants. They rarely enter homes, but are commonly seen crawling on porches, foundations and decks where they may be confused with carpenter ants, because they are similar in size and coloration. (The thorax of a carpenter ant, when viewed from the side, is evenly rounded while that of a field ant is clearly uneven in shape.) The ants feed on insects and the sweet honeydew produced by aphids and similar insects.
Field ants are common in yards, landscaping, fields and wooded areas. They build medium-sized mounds up to 12 inches in diameter, but more often nest under stones, logs, landscape timbers and porch slabs.
Since field ants do not invade houses, they usually do not require treatment. If colonies are located where they might be deemed unsightly, individual mounds may be treated with an appropriately labeled pest control product.