Here’s something interesting: hornworms’ hemolymph (blood) is blue, coloured by a protein called insecticyanin. The foliage they eat contains carotenoids, which are primarily yellow in hue. The resulting combination (blue + yellow) gives them their green colouring. If fed a wheatgerm-based diet in a lab, these caterpillars are turquoise due to the lack of carotenoids in their diet.

Both tobacco hornworms and the very similar tomato hornworms are big fans of Solanaceae (nightshades like tomatoes, potatoes, peppers, tobacco), but they also eat crucifers, legumes, eucalyptus, ficus, and other plants.