Even after cracking all those tomato plant hornworm eggs, I'm still finding more caterpillars on my plants, including a few that have been badly parasitized by whatever it is that makes those white things on their backs. They've gotten to some of my actual tomatoes, eating big chunks out of them. I've been cutting off the stems they're on, putting them in water picks and sticking them in the soil of the big container that had a tomato growing in it - it was going to be the plant I gave the hornworms, but it's just a skeleton of one now. Wagner says that tobacco hornworms have 7 diagonal lines and tomato hornworms have 8 with an extra horizontal line along the bottom making the diagonal lines look like sideways 'Vs' - mine all have 7 diagonal lines, no white line across the bottom, plus all their horns have turned red, so they must all be tobacco hornworms/manducca sexta. I'm just going to let them find their own place to tunnel underground - there's plenty of it out there! I've been feeding them the stems on my tomato plants that are in shady spots that will never flower and make tomatoes, like the lowermost leaves and others. Several times people have asked how I got interested in butterflies and moths. After finding so many stripped tomato plant branches and tomatoes that had been bitten into, I remembered that it was actually tomato/tobacco hornworms that prompted me to really get into wildlife. It was all the beautiful butterflies I saw on this property when we first looked at it that really made me want to buy it. Then after we moved here, I enjoyed the butterflies, but didn't study them, much less raise any myself. I planted a garden each spring like I did when I lived in town - in town, I'd get an occasional hornworm, but they didn't do enough damage to worry about. After we moved here I'd hardly get any tomatoes at all because of the JILLIONS of huge hornworms that totally devoured my plants. The weeds grew more rampantly than they ever did in town, too. I finally decided that the only way I'd ever be able to grow tomatoes or other vegetables here was to use vast amounts of insecticides, which is something I didn't want to do - this has got to be one of the "buggiest" places in America! Since I couldn't lick 'em, I joined 'em! The grocery store has plenty of vegetables, I thought, so that's where I'd get them. I made this picture of two of the tobacco hornworms - notice that one has dark lines and the other doesn't - MissSherry

I think the info you want is available in this study or one of its references (but I don't have time to dig through it). "Effects of parasitism by the braconid wasp Cotesia congregata on metabolic rate in host larvae of the tobacco hornworm, Manduca sexta" Published in Journal of insect physiology, Vol. 43, No. 2, pp. 143-154, 1997 If you give me your email address, I can send you the article in a PDF. I'll warn you that it is not something you would read for fun. From what I read, I learned that caterpillars produce CO2. It makes sense but I had not thought about it before. KC

You asked " Why is it eating tomato, not tobacco plants! " Because that's what they do. If you rear it out, you should get a large showy moth.

Did you capture them to raise them? Caterpillars have their own time frame for growth and development and don't (can't) proceed through the steps of metamorphosis on command. To raise them, they must be provided a clean, well ventilated cage and plenty of fresh clippings from tomato plants. The plants I see in the picture don't look like tomatoes. Perhaps your captives have starved? You haven't given us enough information about their environment.