24 CIRCULAR 8 4 9. U. S. DEPT. OF AGRICULTURE 



climbing the plant and feeding on the foliage, and boring into tomatoes 

 and eggplant fruits if they rest upon the ground. Crumb (o) reports 

 that when tobacco plants become too large for the larvae to sever the 

 stem, they climb the plants, sever the midribs of leaves near the base 

 of the plant, and then feed on the portion lying on the ground. He 

 also says that the larvae can live at least a month on dry vegetation. 



In the central Great Plains the larvae have been collected most 

 frequently in the fall in alfalfa just beneath the soil surface, and some- 

 times even partly exposed. Dust particles covering the body make 

 detection difficult in such places. 



Seasonal history. — Jones reports this species produced five full 

 generations annually in the South, and a partial sixth in Louisiana. 

 Crumb states that in Tennessee there are three full broods and a 

 partial fourth, and that the species overwinters as a pupa. In the 

 central Great Plains region larvae were never found in abundance, 

 so that the seasonal history is incomplete. Adults were taken at 

 lights in Manhattan, Kans., from April to October, the greatest 

 number in September. This leads to the belief that the species does 

 not normally hibernate in the latitudes of the Great Plains, but 

 reestablishes itself each year from northward migration of the adults. 



Life cycle. — Summer generation: Eggs deposited on July 30 hatched 

 in 5 days. The periods required in the various stages were as follows: 



Stage — Continued Period 



Instar — Continued (days) 



Seventh.. 14 to 16 



Stage : 



Period 



Instar: 



(days) 



First 



3 



Seeond 



2 to 4 



Third 



2 to 5 



Fourth 



2to5 



Fifth 



3to7 



Sixth 



5to9 



Total 38 to 40 



Pupa 21 



Egg to adult 64 to 66 



Fall generation: Eggs deposited on September 10 hatched in 6 

 days. During the winter the larvae were kept in a cave where the 

 temperature never fell below the freezing point. Out of 138 larvae, 

 however, only 1 reached the adult stage, although all pupated be- 

 fore November 1. This development would indicate that the species 

 is not adapted to the region, even when protected from freezing tem- 

 peratures, for the pupal period is extended beyond the limits of 

 tolerance of the species to low temperatures. 



Most of the larvae in this series molted five times, but a few passed 

 through an additional instar. The periods required in the various 

 stages and the width of the head capsule in the different larval instars 

 were as follows: 



Stage: Period Width of head 



Instar: (days) capsule (mm.) 



First 2 to 3 0.35 to 0.40 



Second 2 to 3 .50 to .60 



Third 3 to 7 .85 to 1.05 



Fourth 3 to 7 1.30 to 1.70 



Fifth , 4 to 6 2.00to2.50 



Sixth 16 to 28 3.20 to 3.70 



Total 33 to 70 



Pupa » 185 



Egg to adult i 253 



1 1 specimen. 



