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INTRODUCTION.
These solitary wasps get their common name from the very hairy females which are wingless,
often brightly colored, and look very fuzzy. However, they pack a very potent sting which
has earned them the nickname of "cow-killee' and "mule- killer'. Various species
are found throughout the United States.
RECOGNITION.
Adults about 1/8-7/8" (3-23 mm) long. Color black, with areas of often very bright
red, orange, yellow, or white. Females wingless, antlike, but lack node on pedicel, densely
covered with hairlike setae giving a fuzzy or velvet appearance, and with a long,
smooth stinger. Males winged, wasplike, hairiness usually much reduced, coloring
usually dull and different from females, and lack a stinger.
SIMILAR GROUPS.
Large bicolored ants (Formicidas) have pedicel
with 1 or 2 nodes, at most with sparse hairs (setae), and antenna usually elbowed.
Male scoliid/digger wasps (Scoliidae) have wing
membrane beyond closed cells with numerous parallel wrinkles.
Other wasps lack extreme hairiness and/or females
with wings.
REPRESENTATIVE SPECIES.
Common eastern velvet ant Dasymutilia
occidentalis (Linnaeus). Length about 5/8- 3/4" (16-18 mm); covered with black
and red hairlike setae, female black with red except on extreme apex of metathorax and lst
and 3rd abdominal segments, male black with red on pronotum, dorsum of thorax, and abdomen
except for lst/basal segment; parasitic on bumble bee Bombus fratemus Smith; found
in Connecticut to Maryland, southeastern U.S., Missouri, and Texas.
Sacken's/Western velvet ant, Dasymutilla
sackeni (Cresson). Length about 3/8-3/4" (I 0-1 8 mm); body black; covered with
long white or yellowish hairlike setae except for legs and underside of body; parasitic on
wasp Bembix occidentalis Fox; found in California, Oregon, and Nevada.
California velvet ant, Dasymutilla califomica (Radoszkowski).
Female length about 3/8-1/2" (8-14 mm); covered with brick-red hairlike setae; found
in New Mexico, Colorado, Utah, and California.
Pseudomethoca propinqua (Cresson). Length
of female about 3/8-1/2" (8-12 mm), male about 3/8" (9 mm); color black except
vertex (top of head) and apical/rear margins of abdomen with golden hairlike setae, wings
of male dark; found in Minnesota south to Texas and westward to Alberta and California.
BIOLOGY.
The larvae are external parasites on the larvae and pupae of primarily bees and wasps but
also on a few species of beetles and flies. The female lays an egg on the prepupal or
pupal stage of the host, her larva eats the host within a few days, and then spins its
cocoon within the pupal case of its host. Most species of velvet ants are believed to be
parasitic in the nests of wasps and ground-nesting bees, but some are thought to dig nests
in the soil and provision them with insects. Some species are known to prey on honey bees.
Females make a squeaking noise when held by the body; best held with forceps to avoid
being stung.
HABITS.
Females are typically seen running somewhat erratically on the ground, especially on bare
or sandy areas; such areas are favored by many ground-nesting bees and wasps. They will
occasionally enter structures for insect prey; observed in second- floor bathroom feeding
on springtails (Collembola) by the senior author@ Males of some species are often found on
flowers whereas, others are nocturnal.
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