18 CIRCULAR 639, U. S. DEPARTMENT OF AGRICULTURE 
broken, oblique, white cross bands. There are usually six pairs of 
orange- “yellow spots on the sides of the abdomen. The moth 1s active 
only at night and remains concealed in some protected spot during the 
daytime. 
The hornworm passes the winter in the pupal stage, and, in this 
area, the first adults of the season begin to emerge between the middle 
of April and the first of May. Egg laying begins shortly after emer- 
gence, and first-brood larvae usually complete their development about 
the latter part of May or the first of June. Second-brood larvae are 
generally present in the field early in July and maintain the infestation 
on tobacco until the harvesting of the crop. Later broods occur after . 
this time, but the number of individuals comprising such broods is 
relatively small. These individuals feed on late tobacco, and to a 
limited extent on tomatoes, peppers, and similar host plants. Three 
complete generations and a partial fourth occur annually in this 
locality. 
FOOD PLANTS 
As far as is known, the tobacco hornworm feeds only on plants be- 
longing to the family Solanaceae. In this area the most important 
food plant of the larvae is tobacco, and only a very limited amount of 
feeding occurs on other cultivated plants of this family such as toma- 
toes, peppers, eggplants, and potatoes. Observations have indicated 
also that, with the exception of jimsonweed, little or no feeding occurs 
on the wild solanaceous plants of this region. ‘The adults obtain food - 
from the blossoms of jimsonweed, tobacco, petunia, and other plants. 
NATURAL ENEMIES 
A number of birds of this area feed on hornworms, and the pupae 
are frequently destroyed by moles and skunks. The green spider 
Peucetia viridans, which attacks the budworm, also attacks the eggs 
and larvae of the tobacco hornworm, and these stages are sometimes 
preyed upon by a small green plant bug, Cyrtopeltis varians (Dist.). 
One of the most important predaceous enemies of this hornworm 
is a large wasp, Polistes fuscatus var. metricus Say, which feeds on 
the larvae. 
A fly, Sturmia protoparcis (Towns.), closely resembling the house- 
fly (Musca domestica .), is the chief parasitic enemy of the horn- 
worm in this locality. The maggots of this fly feed within the body 
of the host larva, ultimately causing its death. In many parts of 
the country a tiny, wasplike insect, Apanteles congregatus (Say), is 
an important parasite of the tobacco hornworm, but in this region He 
attacks are extremely rare. 
Occasionally dead hornworms may be seen hanging head down- 
ward from the under surface of tobacco leaves. The bodies of such 
larvae have become blackened, and they are nearly twice their normal 
length owing to the stretching of the skin. They have been killed 
by a bacterial disease which is prevalent in the field during periods 
of hot, humid weather. This disease, however, is of only minor 
importance as an enemy of the tobacco hornworm in this area. 
The natural enemies of the tobacco hornworm are undoubtedly of 
considerable importance in keeping its numbers down, and if it were 
