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HYMENOPTERA, Mutillidae (Stephans 1829) - (Vespoidea) (grouped with Sapygidae) --

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Description & Statistics


Mutillidae is family of wasps whose wingless females appear as ants. The name "velvet ant" refers to dense body hair that may be various colored from red to white.. They inflict an extremely painful sting, Ancient velvet ants occur in Dominican Republic amber (25 to 40 million years old). Mutillids occur worldwide, with a total of ca. 5025species, mostly in the tropics. They are common in desert and sandy areas, with most of the over 405 North American species found in the Southwest, and adjacent parts of Mexico, with others occurring in sandy parts of every other state in the USA and Canada; the same habitat where their hosts, ground-nesting bees and wasps, are most diverse. Many are nocturnal, especially in desert areas.


These insects invade the nests of wasps and bees but their integument is very tough which protects them against stings. The males have wings but females are wingless. They exhibit great sexual dimorphism; the males and females are so different that it is difficult to associate the two sexes of a species unless they are captured while mating. Males of some species are much larger than the females.


Only the females sting with their ovipositor. A structure on the metasoma is used to produce a squeaking, or chirping sound when disturbed. Both sexes bear hair-lined grooves on the side of the metasoma called felt lines. The segments of the female mesosoma are uniquely fused.


Mature wasps feed on nectar. Although some species are nocturnal, female mutillids are usually observed scurrying about during the day. Females of Tricholabiodes thisbe are sometimes active until near sunset. Guido Nonveiller (1963) suggested that Mutillidae are stenothermic and thermophilic; they may not avoid light but rather are active during temperatures which occur only after sunset but on cool overcast days could occur earlier. They are social.


Females enter an insect nest, typically a ground-nesting bee or wasp nest, and deposits eggs near the larvae or pupae. The young develop as an idiobiont ectoparasitoid, eventually killing and eating its immobile host.


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References: Please refer to <biology.ref.htm>, [Additional references may be found at: MELVYL Library ]


Ferguson, G. 1962. Univ. Calif. Publ. Ent. 27: 1-92


Hurd, P. D. 1951. Calif. Insect Survey Bull. 1: 89-118


Lorus J. Milne, National Audubon Society Field Guide to North American Insects and Spiders (Audubon Society Field Guide) (Turtleback)(1980) Knopf. ISBN 0-394-50763-0.


Mickel, C. 1928. U. S. Nat. Mus. Bull. 143: 1-303.


Nonveiller, G. Catalogue of the Mutillidae, Myrmosidae and Bradynobaenidae of the Neotropical Region including Mexico (Insecta: Hymenoptera). SPB Academic Publishing bv, the Netherlands, pp. 1150.


Schuster, R. 1958. Ent. Amer. (n.s.) 37: 1-130.