Two species of Hogna, sometimes confused with each other, are among the largest found in the United States, Hogna carolinensis and Hogna helluo.
Hogna carolinensis females may have a body length of from 22 mm (0.87 in) to 35 mm (1.4 in), and Hogna helluo from 18 mm (0.71 in) to 21 mm (0.83 in), with males somewhat smaller. They are fairly easy to distinguish from each other both in gross physical appearance and in their behaviors.
The carapace of H. carolinensis is characterized by an overall dark brown coloration, usually without any patterned variations. Its abdomen has a slightly darker stripe down its center, and its ventral side is black. This spider typically dwells in a vertical tube dug into the ground that may reach as deep as eight inches.
The carapace of the somewhat smaller H. helluo is characterized by a clearly defined medial stripe from a point between the middle pair of eyes nearly to the point at which the carapace joins the abdomen. The abdomen has a broader light stripe with a darker narrow and tapering form like the head of a lance or a stone arrow point. The underside of the cephalothorax is solid black, but the underside of the abdomen may be spotted with lighter colored patches. This species does not dig tunnels but may create shelters under rocks and similar natural features. H. helluo frequently enters houses with the arrival of lower temperatures in autumn. They are inside only in search of warmer temperatures and make every possible effort to stay away from people.