Temnothorax curvispinosus

Acorn Ant
Temnothorax curvispinosus

 

Identification:

Worker: Body is brownish-yellow to reddish. Head dull and grooved. Antenna pale yellow, base (scape) is short not reaching top of head. Antenna 11 segments with short white hair, club is 3-jointed. Lower face (clypeus) slightly protruding. Mandibles pale yellow, toothed, with a black spot on each tip. Thorax dull, grooved; shoulders slightly angled. Top of thorax rounded. Main ID: End of thorax has a pair of long, slender spines, slightly pointing upward. Legs pale yellow, thighs (femora) has dark streaks. Between thorax and abdomen (pedicle) has 2 blunt nodes. Abdomen short, smooth and shiny, segment 1 dark brown to black streak down center.

The Acorn Ant Temnothorax curvispinosus queen at moth sheet July 12, 2011. Wheatley, Ontario.
The Acorn Ant Temnothorax curvispinosus queen at moth sheet July 12, 2011. Wheatley, Ontario.

Queen is similar to worker, but top of head is dark. Thorax brownish-yellow to reddish, shiny, segment 2 (scutellum) dark, rounded. The pair of spines at end of thorax are shorter and wider than the worker.  Abdomen has a wide dark band across middle of the 1st segment and a thinner brown stripe at end of the other segments.

Male is same as worker, only darker with very large, black eyes. Antenna base (scape) short. No spines at end of thorax.

Size: Worker 2.75 to 3.5 mm long, Queen 3.5 to 4 mm long.

Flight Time: June to July

Habitat: Forests and meadows.

Food: Tiny insects, honeydew on leaves, seeds.

Life Cycle: Lives in small colonies of usually 25 to 50 workers, seldom reaching 200. Nests in Goldenrod galls, oak galls; hollow twigs and acorns at ground level. One acorn can hold a nest population of 113 individuals. May have multiple queens in one nest. Workers are active throughout the day. They do not tend aphids. Ant will play dead if handled.

Slave-maker ant Protomognathus americanus have been recorded a few times in the nests of Temnothorax curvispinosus. Apparently the ants rebel and kill the new slave-maker queens larvae.

Comments: Recorded from Wellington County. Also in Michigan. Essex County per photos.

Synonyms:
Leptothorax curvispinosus, Stenamma gallarum

References:
Proceedings from the Academy of Natural Sciences of Philadelphia, 1903, Vol. 55, pg. 239-241 by Wheeler.
Canadian Entomologist, 1909; Vol. 41, pg. 26 by Wheeler.
Antwiki: http://www.antwiki.org/wiki/Temnothorax_curvispinosus