Tetramorium caespitum (Linnaeus) and Liometopum luctuosum W. M. Wheeler (Hymenoptera: Formicidae): new state records for Idaho and Oregon, with notes on their natural history.
Tetramorium caespitum is recorded from Idaho for the first time, with additional records for Oregon. This species was found almost exclusively in urban or disturbed environments. Workers were observed gnawing through wheat stems to obtain individuals of Diuraphis noxia which they carried back to the nest. T. caespitum has replaced Lasius neoniger in at least 2 instances in Idaho. Liometopum luctuosum is reported from Idaho, representing a new Pacific Northwest record. This species was collected from inside houses and from a rangeland area.