Wednesday, September 16, 2009

Parasite Infestation

 
This unfortunate Sphinx Moth caterpillar fell victim to a parasitizing wasp called a Braconid Wasp. This is the first time I've ever seen anything like this and I was taken aback by the severity of the infestation. I was very surprised that the caterpillar was still alive and crawling around. I've been unable to get a positive ID on the caterpillar so I have no idea what moth it would have grown up to be. It obviously had been parasitized by the braconid at a very early stage as the caterpillar was only about an inch and a half long. 
Braconid wasps are notorious for using sphinx moth caterpillars as hosts for their offspring. The female will deposit her eggs, using a very tiny thin ovipositor, under the flesh of the caterpillar. These eggs hatch and the tiny larva will eat their way through the insides of the caterpillar. Once the parasites have reached their full growth they will emerge through the skin of the caterpillar and form cocoons. They will remain in these little white cocoons for several days, finally emerging as adults to carry on the process. The unfortunate victim, the caterpillar, will perish. In the picture above you can see the tops open on the cocoons, which means these wasps have already fled the scene. 
As gruesome as this looks and sounds, it is just one more way that populations are controlled by Mother Nature. The wasp is just doing what it is designed to do, survive.

8 comments:

  1. Nice post! The caterpillar is indeed that of a sphinx moth, but I'm not sure which one. The sheer number of caterpillars out there must be astronomical considering how many things eat them! We should be astounded that any of them survive to adulthood.

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  2. Thanks Eric. Good thing moths are prolific..lol

    I did a double-take when I found this caterpillar.

    The caterpillar was on a lilac, but I am uncertain if it had been feeding on the lilac or if it just crawled there and was living out its final moments there. I couldn't find many records of sphinx moth caterpillars that use lilac as a host.

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  3. Note to self. Don't check out mobugs' site before going to bed.

    (Eeeeeeeeeeeeeeeeeeeeeeeee!!!!! I'm still wincing.)

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  4. Maria, your comment cracked me up...it is creepy though isn't it?

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  5. It's sort of bedtime now and I have NO IDEA WHY I CAME BACK TO YOUR SITE AT THIS HOUR. What is the matter with me? Your stories are too compelling, I guess. Anyway, I'm getting used to spiders. Feeling pretty comfortable with that too...not getting in their way...too much. But OMG, your photo of the momma wolf spider with her hitch-hiking babies? In your OFFICE????? Near your feet?????? Eeeeugh. Eeeeugh. Eeeeeeugh. That's beyond wince-able, that makes my neck shrink into my shoulders while I shiver. Eeeeeeeeeeeeeee!

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  6. LOL, Maria you are a crack up. I will say that spider gave my boss quit a start. He was determined to squish it. Once I told him that those were babies and that if he tried killing her there was a pretty good chance those babies would make a break for it, he decided it might be best to let me scoop her into a cup and contain her until I could release her. They make me shiver for sure. I love insects, but spiders just freak me out!!!!

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  7. My son has one of these caterpillars living on his pepper plant outside our house. He named her Layla and was planning to take her to school with him so his classmates could watch her form a chrysalis. Is this a bad idea? She too has quite a few of these white cocoons on her body. We assumed she was "pregnant" and those were her babies. Are they really killing her? Should we attempt to remove them?

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  8. How wonderful that you have one of these large caterpillars. As gruesome as it sounds, yes your caterpillar is indeed infested with parasitoids. Those white egg-like projections are the cocoons of the brachonid wasp which uses sphinx moth caterpillars as their host quite frequently. Even though it seems sad, it is mother nature at work, and those little wasps need to survive too. Your son could take the caterpillar to school with the cocoons on it and explain to the class what is happening to the caterpillar and that while the caterpillar is destined to perish, those wasps will hatch and carry on their life cycle. So much of the time in life something must die in order for something else to survive. These are also good life lessons for children (as long as they are old enough)

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