Discovered two of the biggest tobacco hornworms I've ever seen on a tomato plant today. I would have called these tomato hornworms before doing a bit of research. The tobacco and tomato hornworms are nearly identical except for two things:
Tobacco hornworm: a reddish horn on the tail and white diagonal stripes on the body.
Tomato hornworm: a black horn on the tail and white (horizontal) "V's" on the body.
These are obviously tobacco hornworms given the reddish horns and white diagonal stripes. They both attack the same kind of plants (mainly tomatoes and potatoes, but also eggplants and peppers) so you may see one or both kinds. I left these alone in hopes that their natural enemy, tiny parasitic braconid wasps, will come and lay eggs on their backs. The eggs hatch and the larvae bore into the hornworm's skin and feed off its body fluids, sealing its fate. The larvae then emerge and create scores of tiny white cocoons which mount vertically on the hornworm's back. The cocoons eventually "hatch" new parasitic wasps which are great for the garden. I'll try to get pics of that if it happens. (Have some from years past but they aren't digital so can't post them.) If they don't become a host for the wasps they eventually fall to the ground, burrow underground and pupate over the winter, hatching into a new brownish-patterned hornworm moths that lay eggs on plants the following year, starting the cycle again.
This one was huge -- nearly four inches long (inside the red ellipse):
This one was shorter, about three inches. The poopy-looking stuff is exactly that -- or frass, to be more exact:
Here's what they do: strip tomato branches perfectly clean of leaves. The hornworms, because of their coloration and the thick foliage of their preferred plants, are extremely hard to spot. But looking for stripped-down branches, and the pills of frass on the tomatoes and branches, is a sure sign a hornworm(s) is lurking:
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