Taken from Hornworms and “Hummingbird” Moths
The tobacco hornworm, Manduca sexta, is usually much more common in vegetable gardens than the tomato hornworm, Manduca quinquemaculata, but both may be found together as they generally have similar habits.
The tomato hornworm has a dark green “horn” with black sides, while that of the tobacco hornworm is red.
The caterpillars also are differentiated by the white striping along their sides. These form a series of 7-8 V’s with tomato hornworms, while there are only 7-8 single diagonal white stripes on the tobacco hornworm.
Occasional dark forms of the tomato hornworm larvae occur. The caterpillars of these are much darker than the normal green, although the adult moths differ little in appearance.
tobacco hornworm eating a meal
tomato hornworm with wasp cocoons