The Mutillidae are a family of more than 7,000 species of wasps whose wingless females resemble large, hairy ants.

Their bright colors serve as aposematic signals. They are known for their extremely painful stings, (the sting of the species Dasymutilla klugii rated a 3 on the Schmidt pain index and lasts up to 30 minutes), hence the common name cow killer or cow ant. However, mutillids are not aggressive and sting only in defense. In addition, the actual toxicity of their venom is much lower than that of honey bees or harvester ants. Unlike true ants, they are solitary, and lack complex social systems. Mutillidae can be found worldwide with approximately 230 genera or subgenera and around 8, 000 species worldwide. Over 400 species occur in the North American southwest.