HORNWOKMS are among the most destruc- 

 tive and widely distributed pests of tobacco, 

 being found wherever this crop is grown in the 

 United States. Since they feed so greedily and 

 move so freely from plant to plant, even a few 

 hornworms can devour or seriously damage large 

 quantities of tobacco leaves. 



Appearance 



Hornworms are the caterpillars, or young, of 

 large, brownish-gray, night-flying hawk moths. 

 In flight these moths are sometimes mistaken for 

 hummingbirds. The caterpillars are 3 to 4 inches 

 long when fully grown and have a large "horn" 

 near the end of the body. They are generally 

 green, but some individuals may be brown to 

 nearly black. Most infestations include two 

 species, the tobacco hornworm and the tomato 

 hornworm. While these species bear a close re- 

 semblance, each has its distinguishing features. 

 The tobacco hornworm has seven diagonal black 

 and white stripes on each side of the body and 

 the horn is curved and red, whereas the tomato 

 hornworm has eight V-shaped stripes and the horn 

 is straight and black. 



Development 



The female moth lays small, round, green eggs 

 principally on the underside of the tobacco leaves. 

 In about 5 days a tiny hornworm emerges from 

 each egg and begins feeding on the leaves. The 

 hornworm continues to feed, pausing only to shed 

 its skin, or molt, four or five times until it reaches 

 full growth in about 3 or 4 weeks. 



The full-grown hornworm burrows several 

 inches into the soil, where it forms a cell and 

 enters the resting, or pupal, stage. The dark- 

 brown, jug-shaped pupae, about 2 inches long, are 

 familiar sights in the soil when a tobacco field is 

 being plowed. Ordinarily this inactive stage lasts 

 from 2 to 4 weeks, but it may continue until the 

 following year. During this period a moth is 

 formed inside the pupa. When the moth emerges, 

 it makes its way to the soil surface, to mate and 

 lay eggs for the next brood of hornworms. There 

 may be one to four or more broods each season, 

 depending upon the latitude and the weather. 



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