The life cycle of the tobacco hornworm begins with an egg that is spherical to oval in shape and measures about 1.5 mm. Egg colors vary and range from light green to white. Eggs are deposited on upper surface of leaves in the lower region of the plant. Eggs hatch in about two to eight days, and the larva emerges. Larvae are cylindrical and have five pairs of prolegs in addition to three pairs of thoracic legs. One of the most striking features of the tobacco hornworm is a thick pointed structure, called a horn, located dorsally on the terminal segment. This horn is normally red. There are seven straight white lines with black edges on each side. The larva develops over twenty days and then molts to the pupa stage. The larva drops to the ground and burrows into the soil where it constructs a pupal cell immediately before pupating. The pupa measures 45 to 60 mm (1 ¾ to 2 ¼ inches). The duration of this stage is dependent on temperature. Adults are large moths with narrow wings that measure about 100 mm (4 inches) across. The forewings are longer than the hind wings. Colors range from dull gray to gray brown, with six orange or yellow spots. The hind wings bear alternating light and dark bands.
The life cycle has about three or four generations per year in Florida while in most other areas it is about two. The insects are active in Florida from August to November. The whole cycle can be completed within 30 to 50 days, but this varies due to cold weather.
Aaron Eichman, Weston Tripp, Matt Edwards
Entomology 301 - Fall 2000