Parasitoids to the Rescue!

Sorry if you’re a little squeamish, but this is too cool to share. Although, I don’t suppose the caterpillar shares my enthusiasm. Last week I found a tobacco hornworm feeding on the leaves of one of my tomato plants. Today I spotted another one. This this one had a problem—a serious problem.

Parasitized Hornworm

See those white things riding on its back? Those are cocoons of a braconid wasp. The Braconidae is a large group of parasitoid wasps. There is at least one that uses tomato and tobacco hornworms as a host for it’s little babies. It injects its eggs under the skin of the caterpillar. When they hatch, the larvae burrow around inside the poor sucker munching as they go until they’re big enough to pupate. Then they pop through the skin, spin a white cocoon of silk and transform into adult wasps that can go on and do that same to more hornworm caterpillars. Isn’t Nature wonderful! The infestation usually kills the host earning the wasps the parasitoid label rather than calling them parasites. I didn’t dispose of this caterpillar like I did with the other one. Here is an opportunity to practice some completely organic pest control. I left them to go about the next stage in their lifecycle protecting the tomato plants of the community garden.

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19 thoughts on “Parasitoids to the Rescue!

  1. That’s a fantastic photograph. On the parasitoid front, if you could manage to keep a population of those wasps I think you could protect yourself from complete obliteration by that caterpillar. It looked as if it could munch through a lot of tomatoes very quickly. Amelia

    1. The do consume a lot of leaves quickly when they get large. And they get large easily because they blend in so perfectly with the leaves. The moths are pretty, but I don’t want to be growing them over tomatoes.

  2. Pingback: Parasitoids to the Rescue! | Shady Character | WORLD ORGANIC NEWS

  3. growntocook

    Such a cool photo! I only read about the parasitic wasps but have never actually seen it in action. So good to know that it actually works – that if you do not interfere, nature will eventually balance itself.

  4. Emily

    It took me a while to see the caterpillar, it’s so well camouflaged! So presumably it doesn’t have long left to live, the wasps will emerge from the cocoons soon. And then do they kill the caterpillar or does it die a natural, exhausted death? Fascinating stuff.

    1. I think it just eventually dies as a result of being eaten on the inside. I found videos of live caterpillars with clearly empty cocoons but maybe they don’t survive pupation.

  5. A wise move!! I would’ve gone even farther and isolated this fat bastard in a nice controlled system and made sure that all the cocoons hatched and then released all these magical wasps back into the garden! Little warriors of awesome!

    From the caterpillars perspective (I know, who cares?) I imagine that it must be insanely freakish to have giant cocoons hanging off of your person!! If we applied the scale to humans, those suckers would be almost as big as your arm! Good luck getting a date walking around with those.

    1. LOL! Yes, we’re lucky we don’t have anything quite that horrifying preying on us. Now you’ve got me thinking of capturing and rearing them next time I find some. I’ve found chewed leaves but no more caterpillars.

      1. I’ve constructed a plexiglass cage for just such ventures. It currently is housing all the giant swallowtail caterpillars I’ve been plucking off of my citrus tree. This way, I get to choose what branches they strip via my careful pruning. My terms! I haven’t the heart to squish them as all critters deserve the right to thrive. Think of it more as indentured servitude.

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