oviposit fertile eggs, which can then be reared. When fed an artificial diet, Manduca larvae do not consume the xanthophyll -which is a yellow pigment- needed to produce their green coloration; instead they appear blue. On some diets, they have very little pigment and pigment precursors, so are a very pale blue-white. As vitamin A and other carotenoids are necessary for the visual pigments (rhodopsin), an artificial-diet-reared hornworm may have poor vision due to lack of carotenoids in the diet. As pet food Captive-bred hornworms fed on an artificial diet are often given to insectivorous exotic animals, such as certain reptiles, fish and small mammals. They are preferred over wild-collected hornworms, which may bioaccumulate poisonous substances found in dietary plants. Hornworms, though originally bred for laboratories, are also farmed for this purpose. They are often sold already packed into pods that include everything the larvae need, including food. Care is relatively easy, and animals seem to relish their bright color and flavor. Subspecies Manduca sexta caestri (Blanchard, 1854) (Chile) Manduca sexta jamaicensis (Butler, 1875) (Caribbean) Manduca sexta leucoptera (Rothschild & Jordan, 1903) (Galápagos Islands) Manduca sexta paphus (Cramer, 1779) (South America) Manduca sexta saliensis (Kernbach, 1964) (Argentina) Manduca sexta garapa (Pixley, 2016) (Saipan) Manduca sexta sexta (Americas) Behavior Feeding Tobacco hornworms are facultative specialists; the larvae can grow and develop on any host plants. However, the larvae prefer solanaceous plants, such as tobacco and tomato plants. On these types of plants, larvae grow and develop faster. The lateral and medial sensilla styloconia (sensory receptors) on their mouthparts help them to identify solanaceous plants by recognizing indioside D, a steroidal glycoside found in those particular plants (del Campo et al., 2001). Salicin is a distasteful phagodeterrent, found only in Salix spp. while caffeine is a phagodeterrent that is actually toxic. Schoonhoven 1969 found that M. sexta habituation to salicin is mediated by desensitization of the deterrence associated peripheral neurons and Glendinning et al 1999 the same for caffeine. However Glendinning et al 2001 find only a small peripheral desensitization for salicin, concluding that Schoonhoven erred, and that habituation in this case is centrally mediated. Tobacco hornworms are considered pests because they feed on the upper leaves of tobacco plants and leave green or black droppings on the plants. As adults, they do not damage plants since they feed on nectar. Tobacco hornworm larvae prefer humid environments. When dehydrated, tobacco hornworm larvae