10 



METHODS OF CONTROLLING TOBACCO INSECTS. 



paring it for the tobacco crop. After the larva 3 , or "worms," have 

 reached this depth they twist and turn many times, finally forming 

 by this action oval cells, in which in a few days they transform to the 

 hibernating form, or pupae (fig. 8). The cells protect the pupa? much 

 better from changes in the weather conditions than if the soil were 

 lying in close contact to them. The insects remain as pupae in the 

 cells during the winter and, as has been stated, begin to emerge about 

 the 1st of the following June as adult moths ready to deposit eggs 

 upon tobacco. 



EMERGENCE OF THE SOUTHERN TOBACCO HOENWORM FROM HIBERNATION. 



Careful records of the emergence from hibernation of the moths of 

 the southern tobacco worm (PMegethontius sexto) were kept during 

 the seasons of 190S and 1909 with very' interesting results. In 1908 

 the emergence began about the last of May and continued until 

 August 13. In 1909 the emergence began June 1 and continued 

 until August 22, a period of 83 days. The records of 1908 were from 

 an emergence of 58 moths. The records of 1909 were taken from an 

 emergence of 1,667 moths, and are, therefore, of more value than the 

 records of 1908. The most interesting part of the data is the fact 

 that in both years a Large percentage of the moths issued after mid- 

 summer. Table II shows the most important data obtained from 

 the emergence records. 



Table II. — Record of emergence of tobacco mollis from hibernation. 



<i Emergence began about June 1. 



b Emergence began June 1. 



From Table II it will be seen that there was a large wave of 

 emergence in 1908 in the 11 days from July 21 to July 31, inclusive, 

 and that 52 per cent of the total emergence took place during that 

 period. The record further shows that after July 15, 5 per cent of 

 the total emergence took place. In 1909 the results were very 

 similar. The large wave of emergence took place during the 11 days 

 from July 29 to August 9, inclusive, and 77.3 per cent of the emer- 

 gence occurred after July 15. 



REMEDIAL MEASURES. 



It has been the belief that the larger percentage of the tobacco 

 worms that appear in late July and in August and September are of 

 the second generation. This is not true, for nearly all the worms 



