Friday, September 11, 2015

Tobacco hornworms and parasitic wasps

You may have seen damage on your tomato plants from tomato or tobacco hornworm caterpillars, and may also have come across hornworms parasitized by braconid wasps, with white cocoons like grains of rice attached to their backs. I wanted to share these great photos taken this week at the Derwood Demo Garden by MG Darlene Nicholson, with her accompanying text.

We are seeing lots of tobacco hornworms chomping at tomato plants in the last week. The one in the image below has been parasitized.


Normally we don't continue to observe what happens after that. This last Tuesday  we actually saw one in a much later transition.  Notice how the hornworm's body is now shriveled and brown and the white cocoons have opened to release a new generation of parasitic wasps.

I am amazed at the built -in structure of the cocoons.  The tops are lightly hinged, with a perfect circular cut. It's all too perfect to comprehend.



You can read more about hornworms at the GIEI website. Remember not to disturb parasitized caterpillars! They will not eat more of your plants. Let the wasps hatch out and go on to make more wasps.

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