Liometopum occidentale

Characteristics – 
Size:  Velvety tree ants measure about 1/4-inch in length.

Color:  The head and thorax are red-brown in color while the velvety black abdomen gives this ant its nickname.

Behavior –  This ant typically lives outdoors where it primarily feeds on the honeydew produced by aphids, mealy bugs and scales that infest trees, shrubs and other plants. Usually, foraging workers will only invade homes when they are searching for food, but they will nest indoors, in wet or rotting wood, or in moist wall voids. Often they are associated with leaks in soffits and around windows and showers. Velvety tree ants may crawl onto and bite a person who is outside working in the yard. 

Habitat –  Velvety tree ants are most common in California, although they may be found in mountain foothills in other western states, as may related species. They nest outdoors in dead and rotting wood and are  associated with tree holes and dead limbs in trees. Active trails of foraging workers easily can be found on the trunks of trees where these ants live.

Tips for Control –  Velvety tree ant colonies in trees may be difficult to control because the nest is located far above the ground. Nests within the wood or voids inside a home require drilling and treatment. These ants may accept sweet liquid or gel ant baits but success will vary. A professional should be consulted when encountering this species.