Subject: This lives my desert milkweed
Geographic location of the bug: Phoenix AZ urban environment
Time: 10:42 PM EDT
Your letter to the bugman: Can you tell us what this beautiful insect is. It has beautiful iridescence on its thorax and abdomen that do not show as clearly in the photo. It is approximately 2.5 inches long with long graceful legs and long wings.
How you want your letter signed: Thank you! Deborah
First we want to compliment you on your wonderful image that is so rich in anatomical details, including the two spines visible on the hind leg joint. This is a Tarantula Hawk and many Tarantula Hawks have bright orange wings and iridescent bodies, aposomatic or warning colors that this wasp can sting and the sting is reported to be quite painful. At first we suspected it was a Mexican Tarantula Hawk because of the black wings, but the large size you indicate has us thinking this is the melanic form of Pepsis grossa based on this BugGuide information: “Very large, with two color forms: Orange-winged (xanthic) and black-winged (melanic). The two color forms are not often seen in the same locality. Melanic forms are easily confused with Pepsis mexicana, but that species is always much smaller in size than P. grossa.” When Tarantula Hawks fly, their long legs dangle behind them. Though they are not aggressive, the sting is reported to be extremely painful. True to their name, female Tarantula Hawks prey upon Tarantulas which they paralyze with their sting. The living but helpless Tarantula is then buried and the Tarantula Hawk lays an egg. When the egg hatches, the larva will eat the Tarantula alive. This is important because if the Tarantula was dead, it would dry up and be useless as food for the larval wasp. Tarantula Hawks are very fond of milkweed. Thanks again for your wonderful submission.