16 CIRCULAR 639, U. S. DEPARTMENT OF AGRICULTURE 
THE HornworMs 
Because of their large size and voracious appetites, the hornworms 
attacking tobacco are capable of inflicting enormous damage to tobacco 
leaves. ‘Two species occur in the southern regions where cigar tobacco 
is produced, the tobacco worm (Protoparce quinguemaculata (Haw.)) 
and the tobacco hornworm (Protoparce sexta (Johan.)). The former 
eccurs in limited numbers and is of little economic importance, but 
the latter is one of the most destructive insect pests of tobacco in this 
area. Owing to this fact only the tobacco hornworm is discussed in 
detail, although the control measures presented are equally applicable 
to the tobacco worm. 
FIGURE 19. eS Tstrowine tobacco stalks Tenodintels after harvest. This prac- 
tice aids materially in reducing the number of late-maturing individuals of 
the budworm, the hornworm, and the flea beetle. 
LIFE HISTORY AND HABITS 
The tobacco hornworm passes through four distinct stages of devel- 
opment during the course of its life cy vele, namely, the egg, the cater- 
pillar, or larva, the pupa, and the adult, or moth. The eggs are 
roughly oval to spherical in shape and are generally oreenish white. 
They are deposited singly by the moths, “usually along the outer 
edges of the lower sur face of the tobacco leaves, although some may 
be attached to the upper surface. The incubation period requires 
approximately from 2 to 7 days, depending upon the temperature. 
Newly hatched larvae are about three-sixteenths of an inch in 
length and are yellowish white. After a short feeding period, how- 
ever, the color changes to pale green, and as development progresses 
the green color deepens and the characteristic oblique black and white 
stripes appear on the sides of the body. The average duration of the 
