In its larval stage, Manduca sexta is known as the tobacco hornworm, a large green caterpillar with a distinctive horn on its posterior segment. Because it can grow to a good size (80 mm), a caterpillar can quickly defoliate its solanaceous plant hosts (mainly tomato and tobacco leaves). While M. sexta is trouble for crops, it is more often described as a garden pest. It is native to the New World and found commonly in the United States as far north as New York, across the Midwest, and through central and South America as far south as Argentina. Manduca sexta has many native predators and parasites that control population numbers, including species of Polistes wasps, big-eyed bugs (Hemiptera: Lygaeidae) and lace wings (Neuroptera: Chrysopidae) which prey on the larvae, and parasites Trichogramma spp., Cotesia congregata, and Hyposoter exigua. Larvae that have been parasitized by Cotesia congregata (a braconid wasp) can be seen covered with white pupal cases of larval wasps that emerged from feeding and developing inside the caterpillar’s body. The adult moth is a large dramatic creature known as the Carolina sphinx moth. It feeds nocturnally on flower nectars. The closely related Manduca quinquemaculata (Haworth) has a similar diet and distribution, and the two are often confused; they can be distinguished as larvae by the white markings along the back of the caterpillar and by the number of body spots on the adult moth. Both species usually produce two generations per year.

Manduca sexta has been developed as a model system for biological study, and is used in laboratories investigating a broad spectrum of topics such as neurobiology, flight mechanics, larval nicotine resistance, and regulation of development. It has several advantages for study, including its large size, short life cycle and the fact that it is easily reared in lab conditions. In the lab the caterpillars are blue because the artificial wheat germ diet they are fed does not contain the yellow carotenoid pigments that normally combine with insecticyanins to turn their bodies green. The tobacco hornworm has also been used for research projects and teaching science in secondary and college classrooms (http://www.manducaproject.com/; http://www.acad.carleton.edu/curricular/BIOL/resources/rlink/).

(Villanueva 1998; Lange and Bronson 1981; Wikipedia 2011)