Other Common Names
Eastern Red Velvet Ant
Cow Killer, Cow Ant (variants of a misnomer applied solely to this species)
Synonyms and other taxonomic changes
[sic] Blake, 1871(1)
Explanation of Names
Dasymutilla occidentalis (Linnaeus 1758)
15-18, 25 (?) mm; the largest and the most frequently noticed eastern Dasymutilla
Females recognized by large size, bold black-and-orange pattern, thorax longer than wide, tip of abdomen has no hair. Hair on dorsal surface may be yellowish, orange, or dull red. Underside is all jet black. Up close, the tips of the middle and hind femora are rounded.
have dark brown wings, have different dorsal pattern from female--thorax, head, and only distal half of abdomen have red/orange hairs.
Meadows, old fields, edges of forests.
Late spring to early fall
Invades the nest of bumble bees, especially Bombus fraternus. Female finds a host nest, digs down and deposits one egg near brood chamber. Larva enters the host brood chamber, kills host larvae, feeds on them, then pupates in the brood chamber.
Females have a rather painful sting, but the species is not medically significant. They are also far more likely to attempt to run from danger before attempting to sting. Also, despite folk knowledge, the sting is definitely not "so painful it could kill a cow" - that is flat out fear-mongering and sensationalist.