icy mound ant

not listed

NNR - Unranked

not listed

Icy mound ant is a northern, cold climate ant. It occurs in formerly glacier covered areas of North America. In the United States it occurs from Maine to New York, west to eastern North Dakota and northern Illinois. It also occurs in southern Canada from Newfoundland to Saskatchewan. It is most common in Maine and New Hampshire in New England, and in Michigan, Ohio, and Quebec in the central Great Lakes region. It is less common in Minnesota. It is found in open fields, early successional shrublands, woodlands, woodland edges, fens, and wetlands.

Icy mound ants have been reported feeding on flower blooms of Queen Anne’s lace and goldenrods, on honeydew, and on smashed apples. They have also been recorded tending planthoppers and aphids. Winged males fly in July and August. Workers forage on the ground, on tree trunks, and on plant foliage.

Icy mound ants usually build large, low, spread-out mounds, but some mounds can be up to 40″ (1 meter) high. The colonies are hosts for the slave-maker ants Pergande’s mound ant (Formica pergandei) and obligate slave-making mound ant (Formica subintegra), and for the temporary social parasite Dakota mound ant (Formica dakotensis).

Workers are uniformly dark brownish-black to black, shiny, and ⅛″ to ¼″ (3.9 to 6.5 mm) in length. They have a pronounced silvery sheen on the head, body, and legs due to numerous flattened (appressed) silvery hairs.

The top of the head is covered with dense, silvery, appressed hairs. It is not distinctly concave. The plate on the face (clypeus) is not notched on the lower margin. On each cheek, the area between the eye and the base of the mandible is not covered with coarse, elongated pits (punctures). The jaws (mandibles) are dark reddish-brown with black edges. Each mandible has one or two offset teeth at the base, the part closest to the head. The antennae are slightly paler toward the base. The basal segment of each antenna (scape) is long, but it is shorter than the length of the head.

The front part of the body (mesosoma) is mostly covered with dense, silvery, appressed hairs. The front part of the mesosoma (promesonotum) usually has no hairs, sometimes just one or two small erect hairs.

The rear part of the body (gaster) has many erect hairs. The first two segments (tergites) are also covered with dense, silvery, appressed hairs. The erect hairs on the first tergite are especially abundant, and the appressed hairs on the third segment are much sparser than on the second tergite. This is an important identifying feature for this species. The glossy sheen of the third tergite is not obscured by hairs.

The legs are slightly paler toward the end except at the tips. They are covered with dense, silvery, appressed hairs.

Total length: ⅛″ to ¼″ (3.9 to 6.2 mm)

Open fields, early successional shrublands, woodlands and woodland edges, fens, and wetlands

Winged males fly in July and August.

Flower blooms and honeydew of aphids and planthoppers

Sources

24, 29, 30, 80, 82, 83.

This species was formerly classified as the subspecies Formica fusca glacialis.

Location: Woodbury, MN