The tobacco hornworm is one of the most common, and also one of the most destructive insects on tobacco. This insect has been more of a mid- to lateseason pest, and one that has the potential for total crop destruction. Due to their size and voracious appetites, if left unchecked, they are capable of total crop destruction.
The tobacco hornworm is a bright green worm that, when full-grown, may be the size of a finger and 3 to 4 inches in length. The most commonly found species in South Carolina tobacco has a red horn on the rear end of the worm and seven diagonal white stripes on each side.
The adults are large moths with a wingspan of 4 to 5 inches, known as hawk moths or hummingbird moths. They are grayish in color, with white and dark markings, and have six orange spots on each side of the abdomen. Females lay their eggs singly upon the tobacco leaves. After larval feeding, the worms transform into pupae and spend two to three weeks in the soil. They also overwinter in the pupal stage.
Non-chemical control practices are of considerable importance in the control of hornworms. Stalks should be cut and destroyed soon after harvest so that overwintering populations cannot build up on sucker growth. Fall plowing will help to reduce the overwintering population. Hand picking of the worms may also be useful, especially if small acreages are involved. Due to their large size, the worms are easily seen and picked off.
Where hand-picking is impractical, the hornworms are easily controlled by several different insecticides. Since the list of labeled products is constantly changing, and since available products varies from state to state, there will be no mention of specific products. With all insecticides, read and follow label instructions carefully.