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TaxonomyBrowse
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Species Dasymutilla occidentalis - Common Eastern Velvet Ant

Pinned Specimen - Dasymutilla occidentalis - male Dasymutilla? - Dasymutilla occidentalis Dasymutilla? - Dasymutilla occidentalis Cow Killer velvet ant - Dasymutilla occidentalis Insect 41 - Dasymutilla occidentalis Cow Killer - Dasymutilla occidentalis - female Velvet Ant - Cow Killer? - Dasymutilla occidentalis Eastern Velvet Ant, 'Cow Killer'  - Dasymutilla occidentalis - female
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Hymenoptera (Ants, Bees, Wasps and Sawflies)
No Taxon (Aculeata - Ants, Bees and Stinging Wasps)
Superfamily Pompiloidea (Spider Wasps, Velvet Ants and allies)
Family Mutillidae (Velvet Ants)
Subfamily Sphaeropthalminae
Tribe Dasymutillini
Genus Dasymutilla
Species occidentalis (Common Eastern Velvet Ant)
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
Mutilla (Sphaeropthalma) Comanche [sic] Blake, 1871(1)
Explanation of Names
Dasymutilla occidentalis (Linnaeus 1758)
Size
15-18, 25 (?) mm; the largest and the most frequently noticed eastern Dasymutilla
Identification
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.
Males have dark brown wings, have different dorsal pattern from female--thorax, head, and only distal half of abdomen have red/orange hairs.
Range
CT-FL west to CO-TX
Habitat
Meadows, old fields, edges of forests.
Season
Late spring to early fall
Life Cycle
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.
Remarks
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.
Internet References