8 BULLETIN 609, U. S. DEPARTMENT OF AGRICULTURE. 



kept outdoors in glass jars transformed to moths 7 days after 

 becoming pupae. 



HIBERNATION. 



This species, judging by analogy, passes the winter months as a 

 larva. The behavior of individuals kept in the insectary, however, 

 should be mentioned in this connection. Larva? collected in the field 

 August 23, October 16, and November 1, 1915, the last date being 

 the latest when larvae were taken outdoors in 1915, were placed in the 

 insectary. Here they constructed above the surface of the soil rather 

 tough, brownish, silken cocoons of a more substantial nature than 

 those from which moths issued during the summer months. Exami- 

 nation of some of these cocoons, made as late as December 11, showed 

 that they contained inactive larvae. The exact date when pupae were 

 formed was not ascertained, but moths began to issue as early as 

 May 10. From observation it would appear that eggs are first de- 

 posited outdoors about this time. 



On October 10, 191G, larvae were found, in cocoons similar to those 

 mentioned above, in a field of sweet potatoes at Baton Rouge. These 

 cocoons were found at the surface of the soil, in portions of old, dead, 

 sweet-potato leaves. 



In southern Texas, according to Mr. High, the last generation 

 doubtless passes the winter in the last larva instar and pupates in 

 the spring or late in the winter. He has observed that the mature 

 larva of this generation spins a cocoon of strong silk during the first 

 half of November and remains in a quiescent state until ready to 

 pupate. The cocoons usually are covered with soil or leaves, although 

 any material the larva is able to draw together may be utilized'. 

 Where no such material is available it will make the cocoon entirely 

 of silk. 



THE LIFE CYCLE. 



The minimum time required for the various stages in the insectary 

 at Baton Rouge was as follows : 



Days. 

 Egg stage 4 



Larva stages 13 



Prepupa stage 2 



Pupa stage 6 



Total life cycle ,-25 



In June larvae were found in a cage 7 days after newly emerged 

 moths had been placed therein, so that it appears that moths may 

 begin egg-laying within at least 3 days after they have issued. This 

 would give a minimum total of 26 days for the life cycle. 



Under normal outdoor conditions the time necessary for the life 

 cycle probably would be somewhat longer than that required in the 



