provided by Catalog of Hymenoptera in America North of Mexico
Females are entirely wingless and have a greatly modified thorax. Males are normally fully winged, but are brachypterous or apterous in a few species. Some females are called cowkillers or mulekillers because of their size and painful sting, or velvet ants because of the appearance of the dense pile covering the body. ~Hosts are known for very few of the North American species. The stages of host attacked are limited to diapausing larvae or pupae. Most recorded North American hosts are wasps or bees which nest in the soil, in borings in wood or which build mud or resin cells or paper nests. However, there is one authenticated record of coleopterous pupae as a host. Extralimital genera have been recorded as parasitizing Lepidoptera, Coleoptera and Diptera, as well as aculeate Hymenoptera. ~Brothers' important contribution on phylogeny of the Mutillidae was received too late to adopt his classification but it will be used in the next edition. He places the Myrmosinae here rather than in the Tiphiidae. He raises the exotic Bradynobaeninae to family rank and transfers to it as subfamilies the Typhoctinae and Chyphotinae (here considered a tribe of Apterogyninae). He assigns the other North American genera as follows: Sphaeropthalminae, Pseudomethocina, Myrmilloides, Pseudomethoca; Sphaeropthalminae, Sphaeropthalmina, Acanthophotopsis, Acrophotopsis, Dasymutilla, Dilophotopsis, Lomachaeta, Morsyma, Odontophotopsis, Photomorphus, Protophotopsis, Smicromutilla, Sphaeropthalma; Mutillinae, Mutillini, Smicromyrmina, Timulla; and Mutillinae, Ephutini, Ephuta.