Velvet ants commonly are encountered in arid, sandy areas of Texas. Although related to wasps, the wingless females resemble ants and have a dense coating of velvety hair. Males have wings and actively fly.

There are many genera and species of velvet ants. In fact, the largest genus (Dasymutilla) contains almost 60 species that have been found in the state. The most commonly encountered and largest species is known as the cow killer, Dasymutilla occidentalis.

Biology

Velvet ants are solitary wasps. Immature stages or larvae feed externally on the prepupal or pupal stages of ground-nesting bees, other wasps and some flies and beetles. The wingless females actively search for hosts on which to deposit eggs. The host is attacked after its cocoon has been spun, or the puparium formed. Upon locating a suitable host, the female penetrates the cocoon or puparium with its long ovipositor (which can also function as the stinger) and deposits one or two eggs.

Eggs hatch and young larvae feed on the host, devouring it. After feeding, the velvet ant larva spins its own cocoon within that of its host. Overwintering occurs as the prepupal stage inside the host's cocoon. Developmental times vary between species and in response to various environmental conditions.

Upon emerging as adults, winged males search for mates. The wingless females attract males of their own species using specific sound produced by a rasping structure located between their second and third abdominal segments. Mating lasts for only a few seconds. Males not searching for females are often found visiting flowers in search of nectar. They do not live as long as the wingless females.

Importance

Females spend much time in sandy areas searching for hosts and may be encountered at close range by adults and children. The females are capable of stinging repeatedly. The stinger is long, and the sting is reportedly quite painful--perhaps the reason that the large common species is called the "cow killer".

People are most often stung by velvet ants on the foot while walking in infested areas without proper footwear. The intensity of pain and reaction to the sting will vary according to the sensitivity of the person stung.

Luckily, these are solitary creatures and the possibility of being stung by a number of these insects at one time is unlikely.

No one has documented the importance of velvet ants as parasites of other insects. Ground dwelling bees, often important in the pollination of some crops such as alfalfa, are known to be hosts for velvet ants. Other species are reportedly pests of white grub parasites, a condition known as hyperparasitism. In each of these different examples, velvet ants can be considered either beneficial or pestiferous depending upon the host species.

Control Measures

Chemical control of velvet ants is rarely justified. The best methods for coping with velvet ants are: 1) the education of youngsters not to handle these insects and 2) wearing shoes in infested areas to avoid accidental encounters.

Occasionally, numbers of velvet ants occur in certain areas such as gardens or underneath houses, trailers or other structures raised from the ground. In these cases, the best control tactic is to eliminate groundnesting wasps or bees on which immature velvet ants feed. For information on controlling the hosts, see L-1828 "Wasps, hornets and yellowjackets".

Individual velvet ants can be killed by crushing or by using directed sprays of household aerosol formulations containing synergized Ryrethrins or resmethrin (SBP-1382 , Wasp FreezeR, and others) that are labeled for wasp control.

Suggested pesticides must be registered and labeled for use by the Environmental Protection Agency and the Texas Department of Agriculture. The status of pesticide label clearances is subject to change and may have changed since this publication was printed.

The USER is always responsible for the effects of pesticide residues on his livestock and crops, as well as problems that could arise from drift or movement of the pesticide from his property to that of others. Always read and follow carefully the instructions on the container label.

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The information given herein is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the Cooperative Extension Service is implied.

Educational programs conducted by the Texas Agricultural Extension Service are open to all people without regard to race, color, sex, disability, religion, age or national origin.

1989

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Last modified: March 18, 1997 by Edgar Cross