Afternoon InquisitionScience

AI: Unusual Byproducts

One of the classic ways in which entomologists try to convince people that they should like insects and spiders, not squish them, is to list all the ways in which they are useful to us.

Personally, I find these little animals fascinating in their own right, but putting numeric values on the economic services provided by bugs makes more people willing to spare them. Nutrient cycling and pollination by insects are estimated to contribute upwards of $55 Billion dollars yearly to the US economy.  It’s easy to make a utilitarian argument for the value of spineless animals.

There are also less well-known byproducts of insects and spiders that have an economic impact. I’ve written before about shellac and cochineal.  This week’s example: A spider venom that causes erections. Or, as it’s described in a recent scientific paper, “spider accident-induced priapism.”

The spider in question is Phoneutria nigriventer, also known as the Brazilian wandering spider.  It’s rather largish (15 cm/5 in), and belongs to a genus of spiders with a name that translates to “Murderess”.  Yikes.

And it gets better! From the Smithsonian:

“A bite from the banana spider (also known as the Brazilian wandering spider) of Central and South American rain forests causes shortness of breath, excessive salivation, tremors and—for men—a persistent, intensely painful erection, known as priapism in the medical community.”

This has been a known side effect for many years, so with erectile-dysfunction drug Viagra making lots of money, it makes sense that the mechanism and cause of “accidental spider erections” would be investigated.  Here’s the title of the most recent paper on this topic:

Erectile Function Is Improved in Aged Rats by PnTx2-6, a Toxin from Phoneutria nigriventer Spider Venom.  The Journal of Sexual Medicine.  Volume 9, Issue 10 2574–2581. October 2012.

The experiments were just about what you might expect from that title. They injected the rats with venom, and…. there was cyclic guanosine monophosphate pathway excitation. Ahem. If you know what I mean.

This isn’t the only arthropod product that is believed to cause erections–you might have heard of “Spanish fly.”   It’s not actually a fly–it’s made from a blister beetle, Lytta vesicatoria–but the mechanisms are vaguely similar. Both the spider venom and the beetle toxins work in a similar way. They relax blood vessels–which in men, and apparently elderly rats, has the happy side effect of increasing blood flow to spongy tissues in the penis.  Boing!

Wandering spiders are occasionally reported in North American or European groceries as inadvertent travelers on fruit. It would be a very stupid idea to stick one on your dick and let it bite you. You might also want to know that the primary use for “spanish fly” compounds these days is wart removal before you go experimenting with blister beetles as well.

Alas, it is incredibly easy to kill yourself with “spanish fly”, and the folks with “spider accident-induced priapism” are not enjoying the experience. We’ll have to wait quite a bit longer before any byproducts are available as prescription drugs.

What about you? Would you take a drug derived from spider venom? What’s the oddest animal byproduct you’ve ever heard of? (Jello doesn’t count).
The Afternoon Inquisition (or AI) is a question posed to you, the Skepchick community. Look for it to appear Sundays, Tuesdays and Thursdays at 3pm ET.


Bug_girl has a PhD in Entomology, and is a pointy-headed former academic living in Ohio. She is obsessed with insects, but otherwise perfectly normal. Really! If you want a daily stream of cool info about bugs, follow her Facebook page or find her on Twitter.

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  1. Spider venom priapism was a plot point in the Chuck Palahniuk book “Rant,” although he seemed to suggest that any spider bite will do it.

  2. I don’t believe cantharidin causes erections; it is an irritant that happens to be excreted via the kidneys and irritates the urethra along with everything else it touches. That might explain why ‘spanish fly’ isn’t as good as an aphrodisiac as we might like to think. I use cantharidin several times a week, along with concentrated salicylic acid and podophyllin in an ether base. Destroys warts very nicely!

    1. Yes, the mechanism varies widely, depending on who you read.
      Everyone does agree it is a BAD idea to take it internally, probably for several different metabolic reasons.

      1. Oh, and I was cleaning my house today, and guess what I found!

        2002. A world view of insects as aphrodisiacs, with special reference to Spanish fly. American Entomologist 48: 208-20. Prischmann and Sheppard.

        “since cantharidin irritates the urogenital tract, tingling and burning sensations are felt in the genetalia, and due to blood vessel dilation, the penis and labia engorge with blood.”

  3. bug_girl,

    As far as I can tell people usually aren’t out to exterminate all the world’s bugs, just the ones that get in our way. That said, they do have an imagine problem.

    1. “As far as I can tell people usually aren’t out to exterminate all the world’s bugs, just the ones that get in our way”

      Aren’t Daleks like that with people?

        1. bug_girl,

          I guess you’re right, if I said that about a group of people I would definitely sound evil.

      1. Grand Lunar,

        I don’t watch Doctor Who, but its my understanding that the Daleks want to wipe out everything else in the Universe. Am I wrong.

        1. Pretty much like that, yes.

          Only put it that way to fit in the context.
          I may never view the word “Exterminate” in an ordinary context again!

  4. -“Would you take a drug derived from spider venom?”

    Only if I needed it and if I could afford it.

    If there’s one for weight loss or pain relief, I’ll take it.

    -“What’s the oddest animal byproduct you’ve ever heard of? (Jello doesn’t count).”

    Only one that really comes to mind is a possible bio-fuel that could be made from termite byproducts. Or maybe a chemical they use.
    Read about it on NASA’s climate change website.

  5. “there was cyclic guanosine monophosphate pathway excitation.”

    I love it with bug_girl talks dirty! ;)

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