By Kathy Feagan
Texas is home to close to 150 different species of Velvet Ants (family Mutillidae). Nationwide, there are about 400 different species. “Cow Killer” Velvet Ants are not actually ants but a species of wasp in the order of Hymenoptera. They get the common moniker of “Cow Killer” due to their exceedingly painful sting (considered to be one of the most painful of all insect stings). Only females have a stinger and they are wingless. Males, who lack a stinger, have wings and fly. Unlike most wasps, Velvet Ants are solitary, parasitoid wasps.
After mating in summer, females hunt for and then sneak into their host’s nest when the coast is clear. She uses her very long and maneuverable ovipositor, which doubles as her stinger, to pierce the larvae, then lays her egg on or next to the larvae. Her sheathable ovipositor also attaches to a venom gland for stinging. The female paralyzes the larvae so it cannot attack the feeding Velvet Ant larvae she will lay. She then exits and seals the entrance to the nest. A few days later, the Velvet Ant larvae hatches and begins slowly eating the host pupa or larvae. Once finished with the host, the Velvet Ant spins itself a cocoon inside the host’s chamber. It then overwinters under the soil until late spring to summer when the adult Velvet Ant emerges to forage, hunt for host sites and find a suitable mate.
Females strive to find host burrows with large, maturing larvae as the size of the adult Velvet Ant is determined by the size of its host. Velvet Ants also have an incredibly hard armor- like exoskeleton that is nearly indestructible. The female Velvet Ant’s very fibrous and layered ‘armor’ shell is fused together without seams or joints. This allows the curved exoskeleton to bend to absorb and dispense force across their entire body without breaking. This protects the female from defensive bites and stings from host insects, especially when she seals the chamber after laying her egg, as well as deterring other predators. Adults live one season to mate and reproduce and then die.
During the hot summer, females crawl rapidly on the ground discharging sex pheromones while males fly low, using their antennae to track the scents. Females and males also rub abdominal segments to make chirping or squealing sounds to help the male find the female. Once the male finds a willing female, the male uses his powerful jaws to grasp the female by the neck and carry her to a shaded, safe area to mate. After mating, most males continue to hold on to the female for up to 2 hours, stroking her thorax, to protect her from rival’s attempts to mate with her. But, some less romantic males release the female directly after mating and fly away. Velvet Ants are carnivorous parasites. They live on a liquid high carbohydrate diet for lots of energy. Most species act as pollinators drinking nectar from flowers. Wood and brushland Velvet Ants drink sweet sap from trees or sugary discharge from leaf stems. In agricultural areas and suburban areas, Velvet Ants prefer rotting berries and fruits.
Red Velvet Ants “Cow Killer”(Dasymutilla occidentalis) are the largest and most common of the species in Texas. Females are wingless and have stingers. They are black with brightly fuzzy, plush red/orange “fur” on their backs. They grow to ¾ to 1” long. They look like giant ants. Males have black wings and no stinger. They are active in the late spring and summer months. You will see a female quickly scurrying in the grass, deck, garden or sandy areas. They prefer dry, arid areas like Abilene. When threatened, females produce a high squealing sound and quickly run away. Females hunt for the nests of large ground nesters like bees and wasps. They prefer cicada killers, horse ground and sand wasps, bumble bees and solitary bees like mining, digger and sweat bees. The adults of this species have been observed eating adult and larvae stages of soft bodied insects like flies and bees, along with the needed nectars.
Texan Mimicry (D. Waco, D klugii) comprise 14 velvet ant species across Texas. They all have a distinctive black head and thorax with a flaming orange abdomen and a red exoskeleton. They are designated as “mimicry rings” due to their evolving into identical insects. Besides hunting the larvae of cicada killers, horse guard and digger wasps, solitary and bumble bees, these species are known to be parasites of mud dauber, paper wasps, beetles and flies. They grow to ½ to ¾” long although the Klug’s Velvet Ant (D Klugii) can grow to over 1” long.
Thistledown Velvet Ants (Dasymutilla gloriosa) are found mainly in desert areas of West Texas. They are covered in long, thick, vividly bright, white hairs. They mimic drifting Thistle seeds (which are painful to eat), concealing themselves perfectly in the desert landscape. They grow to ½ to nearly ¾” long. Their white hair reflects the relentless desert heat and acts as a thermal shield by creating a pocket of air to cool the wasp’s body as it hunts. If attacked, they emit a chemical secretion from their mandible glands and make their loud, warbling squeak to frighten their attacker. If these acts fail, the female will deliver a very painful sting with her ovipositor. This species eats mostly the moisture and secretions of desert succulents, cacti glands, acacia trees and dew. The female lays an egg one at a time in the nests of ground dwelling sand wasps, solitary bees and thread waisted wasps (digger and mud dauber wasps). The female can use pheromones to disguise her presence while digging a separate entrance to the nest or finding an unguarded nest. If that fails, she fights the host using her armor and her stinger, forcing the host to retreat.