Found it on my tomato plant. I'd seen them before in sizes up to 4-5 cm. They eat the tomato leaves like crazy. And (naturally) poo a lot. Some black granade like aggregates. Once grown they molt into a moth that I saw a few days ago. And now my tomato plants are again riddled with these buggers.
This photo was done with the help of a stereoscope. The grid squares are 4mm inside, and 5mm outside the lines. So this juvenile has about 1cm.
I'd love to ID them. Any advise on how to control them without pesticides is also welcome.
It's a long shot, but could it be a Tiger Swallowtail Butterfly Caterpillar? They've got a line of faint dots down their sides and have no horn, but they're about the same size and color as a hornworm.
Would be lovely, but the butterfly/moth is quite a bit less colourful.