Sunday, August 07, 2011

Giant ichneumon wasp
(Megarhyssa macrurus)

I was digging up the irises around the birch stump today. We're going to have it ground down so we can plant another tree there. A long insect came zooming by and landed on the stump. I thought it was a dragonfly until I saw its tail.
My goodness! Is that a stinger? I grabbed my camera to take some photos. When the creature start to lift and flare its abdomen, I backed off, thinking that was some kind of threat display.

Then I went inside to look up what it was. What she was – a female Megarhyssa macrurus, or giant ichneumon wasp. What I thought was a stinger is really a 6-inch-long ovipositor. She was looking for holes bored by her rival, a pigeon horntail wasp.
When she finds one, she lifts her abdomen high in the air and draws that long ovipositor forward until she can push it straight down into the hole, guiding it with her hind legs. In the hole is the larva of her rival, which she stings and paralyzes. Then she lays an egg, which will hatch and eat the paralyzed larva, then pupate and become an adult wasp the next spring.
Ew, right? But very interesting. It's so specifically evolved. (If you're not too squicked out, click to see the photos larger; they're pretty cool.)

It's funny, the Sergeant and I were discussing the theory of intelligent design and its flaws just last night. Turns out Darwin had something to say about that, involving the ichneumonidae's gruesome habits:
I own that I cannot see as plainly as others do, and as I should wish to do, evidence of design and beneficence on all sides of us. There seems to me too much misery in the world. I cannot persuade myself that a beneficent and omnipotent God would have designedly created the Ichneumonidae with the express intention of their feeding within the living bodies of Caterpillars, or that a cat should play with mice.
Thanks to the fine contributors to Wikipedia for expanding my insect horizons. And thanks to Ms. Wasp for stopping by. I'm sorry that your efforts will be in vain.

11 comments:

  1. Great pics, as always. I've seen this one before, but never knew what it was, so thanks for the entomology lesson. How interesting!

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  2. Those are awesome photos of an incredible wasp! I've seen multiple ichneumons before, but never one of that size or with that long an ovipositor. And to be able to watch her probe for a pigeon tremex larva! Absolutely wonderful.

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  3. How fascinating! I have never seen one of these wasps before...your garden must be very healthy, you seem to have all types of bugs in it!

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  4. Wow! Great shots as always. And a lovely Charles Darwin quote to top off a very interesting post. If I'm ever stuck on a desert island I want a stack of his books and that will do me just fine. Get back to us if you figure out the "intelligent" part of "intelligent design." Until then, I'm sticking with random design. (Or is that an oxymoron?)

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  5. Wow, thanks for the education today. It is very interesting. Fascinating!

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  6. I have one in front of me BC it was flying around my 4 year old son who's allergic to bees. I swatted it and killed it. The stinger is 6 inches long and it has 3 of them!! Strange :/

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  7. A strangely beautiful creature. Thanks for the ID. The world is a wonderful place, full of surprises.

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  8. You didnt have to kill it, they dont sting.

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  9. I just saw one in the back yard and came running. I'm terrified of honey bees so, as you can imagine, this was my nightmare! Good to know it's not some crazy killer wasp so I will leave her alone to do her thing. Thanks for the info!

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  10. Thanks for the post. I recently found one in my yard and got 2 pictures of it, but I'm not sure how to post them here. Anyway, thanks for your post.

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