Wednesday, June 17, 2009

Tarantula Hawks On the Loose!

Tarantula hawks (Pepsis sp.) are most active in the summer, during the day, although they avoid the highest temperatures. They are one of the largest species of wasps in Texas. They are 1 ½ inches in length, metallic blue-black in color with red wings. Tarantula hawks are considered generally harmless to humans, since they seldom sting. However they can be provoked, so they should be left alone; their stings are considered to be the most painful of any North American insect.
Tarantula hawks get their common name since they use tarantulas as food for their immature stages. These wasps are found wherever tarantulas are found since tarantulas are needed for the continuation of the wasp’s lifecycle. The female wasps will either enter a tarantula burrow and push out the spider, or attack a male tarantula while he is searching for a mate. She will grab the spider by a leg, flip it over on its back and sting it, or she may approach it from the side to deliver a sting. Once the tarantula is stung, it becomes paralyzed within seconds.
If the female wasp expelled the tarantula from a burrow, she will drag it back into its own burrow and lay a single egg on the spider’s abdomen. Then the burrow will be sealed. If the female wasp stings a male tarantula in search of a mate, the female wasp will excavate a burrow and drag the paralyzed spider inside. Then she will lay her single egg and seal the chamber. Once the egg hatches, the wasp larvae begins to feed on the tarantula and develops within the burrow.
Male tarantula hawks usually perch on taller vegetation or high points, where they wait for newly emerged females, which may be receptive to mating. Both male and female tarantula hawks feed on nectar.

A tarantula hawk, Pepsis sp. (Hymenoptera: Pompilidae). Photo by Bart Drees, Professor and Extension Entomologist, Texas A&M University.

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