by LeCnny Vincent
The Preservation News. November. 1999
The Velvet Ant.
I saw my first velvet ant many years ago. It looked like a large, compact
ant covered in rich, straight-out red velvet. It was beautiful, and I
was tempted to pick it up. Then, at the last minute, I remembered its
common names, "cow killer" or "mule killer," referring to its extremely
painful sting! Not too surprising, maybe, as the velvet ant is actually
Ants, bees and wasps belong to the Hymenoptera. This order contains many
beneficial insects that pollinate our crops and native plants, and eat
or parasitize pest insects. Ants have knobs on their narrowed waist (the
section that joins the thorax to the abdomen), bees have feathery hairs
all over their body, and wasps have neither a knobbed waist nor feathery
hairs. Velvet ants belong to the wasp family Mutillidae and can be referred
to as mutillids or, as an individual, a mutillid. Only female wasps can
Adult velvet ants are usually brightly colored. They can be deep red,
orange, or yellow. Occasionally I have found white ones. Often you can
see black bands encircling the abdomen. Mutillids are hard to identify
in the field because a given species may take various color forms in different
areas. There are over 500 species in America north of Mexico, mostly in
the South and West. Adults are 5 to 20 mm (about 0.25 to 0.80 inch) long.
Females are wingless, males are winged and usually larger. Some species
make a squeak (stridulate) when disturbed.
Velvet ant larvae are external parasites on the larvae and pupae of solitary
bees and wasps that live in underground burrows. A few species parasitize
beetle and fly larvae. Adult female velvet ants search on foot for sandy
areas, their preferred habitat, to locate the underground nests of their
hosts. If the wasp or bee nest is sealed, the velvet ant will chew its
way in. Once inside, the female finds each helpless cocoon, bites a small
hole through the cocoon wall, and inserts a single egg on the developing
bee or wasp. She then plugs up the hole using a mixture of salivary secretions
and sand and departs to search for more burrows to infiltrate. Soon her
eggs hatch, and the white legless velvet ant larvae slowly consume their
Adult velvet ants apparently are not host specific. An individual mutillid
may attack wasps or bees that belong to different genera or even families.
Some species of velvet ant have been observed attacking full-grown bees
and wasps. The velvet ant bites a hole in the neck of its victim and sucks
out the body contents. Velvet ants have an unusually thick exoskeleton,
a suit of armor, that probably serves to protect them from the stings
and powerful bites of nest-defending bees and wasps.
Velvet ants are easily found walking in areas where their hosts nest.
These are often open, arid sandy areas. I have seen velvet ants walking
on trails in Laguna Coast Wilderness Park from February to October, usually
in the afternoon. Their bright colors, which make these insects highly
conspicuous and memorable, are probably warning signals (called "aposematism")
for potential predators such as birds, lizards and unsuspecting humans.
Potent stings, like those of the diminutive cow killer, are not soon forgotten.
Lenny Vincent teaches biology at Fullerton College and is
on the Board of Directors of the Laguna Greenbelt, Inc.