7/29/12 Tarantula Hawk (Pepsis formosa) feeding on the nectar of Rush Milkweed (Asclepias subulata) in the desert garden. Milkweeds seem to be their fav.
Ok, these extremely large (2") and colorful wasps are not to be trifled with, especially if you're a tarantula, cuz, just like out of a horror sci fi flick, the mama wasp will want to lay a single egg into the tarantula's body, which will serve as a living food source for baby wasp as it eats its way inside out before it finally pupates. O M G!!!
Lucky for us, Tarantula Hawks are not especially aggressive towards humans unless provoked, so do so at your own peril and if you're dead set on winning a Darwin award, because the pain from the sting, although short-lived, is apparently beyond excruciating (from Wiki):
Commenting on his own experience, Justin O. Schmidt, entomologist and creator of the Schmidt Sting Pain Index, described the pain as "…immediate, excruciating pain that simply shuts down one's ability to do anything, except, perhaps, scream. Mental discipline simply does not work in these situations." In terms of scale, the wasp's sting is rated near the top of the Schmidt index, second only to that of the bullet ant, and is described by Schmidt as "blinding, fierce [and] shockingly electric".