Pepsis Grossa — Behemoth

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Today’s featured species is Pepsis grossa, known colloquially as a “tarantula hawk.”  I suspect that some people might find the latin name to be apt because their reaction upon encountering this two-inch wasp would be to declare:  “Ewwww, gross!”  However, I think that they’re beautiful, and are in fact, among the most striking creatures that I photograph.

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I photographed these wasps yesterday morning at Tohono Chul Park, a privately operated park on Tucson’s west side.  There were a dozen or more of them feeding on the nectar produced by milkweed flowers.  These gigantic  wasps paid me no attention whatsoever as I photographed them.  I stood within inches of them as they fed and at no time did they react to my presence even as I took one flash picture after another.  Indeed, one of them briefly landed on the back of my hand, perched there for a couple of seconds, and then flew over to the flowers where it began to feed.

The immense size of these wasps evident in this next picture.  The little insect in the background of this photo is a Milkweed Bug.  It is about 1/3 of an inch in length.  The wasp is easily six or seven times its size.

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One can easily identify these wasps by their immense size, their cobalt-blue bodies, and their brilliant orange wings.  I was surprised to learn, however, that there is an all-black morph of this insect which is simply a melanistic version of the same species.  I saw one of those yesterday but was unable to get a decent image of it.

Tarantula hawks get their nickname because females of the species hunt tarantulas.  One will engage in combat with a tarantula, seeking to paralyze it with its sting.  If successful, it buries the spider with a single egg.  The larva feeds on the paralyzed, but still living spider, killing in the process.  So, for every one of these wasps there is a dead tarantula somewhere.  One sees a lot of tarantula hawks while walking in the desert, and that suggests that there are an awful lot of tarantulas out there.

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Male tarantula hawks, as opposed to the females, lead a carefree existence.  No battles with tarantulas for them!  Nope, they feed on nectar all day long, hang around milkweed plants, and wait for receptive females to show up.  Then, it’s sex and back to nectar drinking.

By reputation, tarantula hawks have among the most potent stings of all insects, supposedly excruciatingly painful.  I was stung on my forearm a few years ago by one of these wasps when I stupidly attempted to brush it off after it had landed on me.  Had I done nothing it would have flown off on its own accord.  The sting was very painful — not a life threatening pain — but definitely memorable.  If you’ve ever been stung by a bee, think of something that is three times as painful and that’s about what it felt like.  The pain was of short duration, but for about five days thereafter my arm itched as if Hell’s imps were playing with it.

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I had been led to believe that these wasps’ long, recurved antennae, which sort of resemble handlebar mustaches, identifies them as males.  However, in researching tonight’s blog I found a website that said that females have longer antennae then males.  I think that’s definitely incorrect, but I’ll note that if only to say that my certitude may be misplaced.

Images made with a Canon 5DS-R, 180mm f3.5L Macro Lens assisted by Canon 600EX-RT Speedlite and stabilized by monopod, M setting, ISO 160, f11 @ 1/160.

One response to “Pepsis Grossa — Behemoth”

  1. Victor Rakmil says :

    Great post, great shots.

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