Ok, this is kinda gross, but also very interesting.  This is a tobacco hornworm on one of my tomato plants.  Usually I get rid of them, but this one is doing a remarkable thing.  

 

There is a parasitic wasp, Cotesia congregata, that oviposits her eggs under the skin of tobacco hornworms.  When the larvae hatch out, they use the hornworm for food.  So, you see, this hornworm is serving a very important purpose:  feeding beneficial insects in my garden, thus reducing the population of hornworms.  

 

The first time I saw this, I had no idea how a caterpillar could lay eggs.  Of course, they don't, but you don't know until you know.  The wasp larvae feed on the caterpillar, then spin their cocoons which pop out through the caterpillar skin.  So, these white fuzzy things on the caterpillar are wasp cocoons.  Natural hornworm population control.  

 

Now you know.  Still kinda gross.

 

 

HAPPY GARDENING!!!