Lacosoma arizonicum, the southwestern sack-bearer moth,[2] is a species of moth in the family Mimallonidae and one of four species of sack-bearers occurring north of Mexico.

[1] The species was first described by Harrison Gray Dyar Jr. in 1898[1] from a single male specimen[4] and has Hodges number 7660.

[5] In addition, captive larvae have also been successfully raised on Quercus virginiana.

[5] Larvae have an enlarged head and a flattened, armored anal plate, both of which are characteristic for species of Mimallonidae.

[5] Wings are pale brown, shaded rosy pink on the basal half, and have an obscure dot on both wings as well as a thin, very slightly curved, brown line.