Black Carpenter Ant Worker

A busy Black Carpenter Ant (Camponotus pennsylvanicus) crossed my path the other day. It was a worker with an apparently important mission, for it was wasting no time and scurrying rapidly across the ground. It was all I could do to keep up with my AF.

Carpenter ants are large (up to 1/2 inch long) and thus easy to spot. Distinguishing features are the yellowish or whitish hairs on the abdomen, the single node between the thorax and abdomen (other ants have 1 or 2), and the even profile of the thorax (other ants have an uneven profile). Like other species of ants, a carpenter ant colony has a caste system. I believe this ant is a "major worker".

Left to right: Queen, winged male, major worker, minor worker
http://www1.extension.umn.edu/garden/insects/find/carpenter-ants/

Carpenter ants can be pests, but make sure they are causing real damage before attempting to exterminate or deter them. 

References:
http://www.fcps.edu/islandcreekes/ecology/carpenter_ant.htm
http://lancaster.unl.edu/pest/resources/carpant004.shtml
http://www1.extension.umn.edu/garden/insects/find/carpenter-ants/
http://ento.psu.edu/extension/factsheets/carpenter-ants
http://www.orkin.com/ants/carpenter-ant/