DASYMUTILLA ERYTHRINA

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 ERYTHRINA

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 ERYTHRINA, with no English name.

According to "geomodel predictions" of Dasymutilla erythrina based on identifications at the iNaturalist.ca website, this species probably occurs throughout most of Mexico's drier uplands, into desert parts of Arizona and New Mexico in the US, and possibly south into Guatemala. George Waldren's dissertation reports that citizen scientist observations contributed to the iNaturalist.org website indicate that Dasymutilla erythrina is the most commonly encountered fire ant species in Central Mexico.

Waldren also makes the point that our species is 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 announce to the world that it's dangerous. 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 being 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.

The 2022 study by Fernando Hernández-Baz and others entitled "Natural History Notes of Dasymutilla erythrina (Hymenoptera: Mutillidae) in Biosphere Reserve Tehuacán-Cuicatlán, México," describes seeing our species at it "spun around" a cactus and hid under bushes and thorns. The movement was fast and gave the impression of being erratic, same as with ours. Another one was seen walking around in an area 1002 meters large (over 1000 square feet). Further it's said that females of this species often are spotted in sunny, sandy, and deserty areas, just as with our individual, and sometimes they are observed after sunset.

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.