To control the Tomato Hornworm (Manduca quinquemaculata) you can….

Handpick the caterpillars from the foliage; spray Bacillus thuringiensis (Dipel) while caterpillars are still small; till the soil in the fall or early spring to destroy any pupae;try growing nectar or pollen plants to attract native parasitic wasps, which usually provide some control in most areas; or release lady beetles or lacewings to attack the eggs.