DASYMUTILLA VESTITA

Excerpts from Jim Conrad's
Naturalist Newsletter

Entry dated May 28, 2024, issued from near Tequisquiapan; elevation about 1,900m, (6200 ft), ~N20.57°, ~W99.89°; long-overgrazed field with areas void of vegetation exposing naked dirt composed of fragmented volcanic tuff, or ash, of varied particle size; Querétaro state, MÉXICO
DASYMUTILLA VESTITA

The above velvet ant moved fast here and there across naked, hard-packed, drought-baked dirt in a large, grossly overgrazed and eroded abandoned field. Its bigger-than-ant size, its color pattern and behavior were exactly what one expects of velvet ants. Velvet ants actually are wasps, and this one was a female because she was wingless; winged males look more like wasps. Not all velvet ants are bright red like this one. For example, in this same field and quite nearby, we've seen a brown and white species, Dasymutilla sicheliana. Of the two species, this red one is by far the most frequently seen.

The 2021 PhD dissertation by George Waldren entitled "The Velvet Ants (Hymenoptera: Mutillidae): Systematics, Biology, and Biogeography of a Little-Known Family," says that at this writing over 4600 described members of the velvet ant family Mutillidae are known, with many awaiting formal description. Back on the farm in Kentucky, we called them cow killers; everyone knew they packed a powerful sting, and we were terrified of them. The Kentucky species, the Red Velvet Ant, Dasymutilla occidentalis, was red and black like this one, and similarly scurried about on sunbaked ground. A search on velvet ants documented in our part of upland central Mexico turns up four species, of which this red one overwhelmingly is the most common. It's DASYMUTILLA ...

*UPDATE: I thought our ant was the most common one, Dasymutilla erythrina, but later in the year when I upload the above picture to iNaturalist, user "kevinwilliams," a velvet ant specialist and a curator with iNaturalist, recognizes DASYMUTILLA VESTITA, which is very similar to Dasymutilla erythrina when seen from above. Moreover, at iNaturalist, ten Dasymutilla species are documented for Querétaro state, of which Dasymutilla vestita is one of the lesser observed, being more commonly seen in western North America than Mexico. In Mexico it's found as far south as Oaxaca.

These red and and black velvet ants are part of the largest of all known Müllerian mimicry complexes. Müllerian mimicry is when two or more well-defended species mimic one another's warning signals, to their mutual benefit. In other words, our velvet ant with its powerful sting uses its attention-getting red-and-black color pattern to announce its defenses. All red-and-black velvet ants in the large region where such individuals occur and produce similarly painful stings benefit from this warning, because it's so frequently and widely confirmed by negligent victims who get stung. Sometimes species which are not velvet ants, such as certain spider wasp species, evolve in a way that they benefit by looking like velvet-ant members of their mimicry complex.

Velvet ant species are solitary parasitoids, in this case meaning that individual females lay their eggs in underground bee and wasp nests, where their hatched young primarily feed on the immature stages of solitary bees and certain kinds of wasps.