COTTON BOLL WEEVIL IN THE MISSISSIPPI VALLEY. 



23 



the same place in 1913 they averaged 212 eggs each at the rate of 5.9 

 per day. That this year's low record is not due to the difference in 

 localities is shown by the fact that at Tallulah in 1910 the weevils 

 averaged 208 eggs per female, at the rate of 5.5 eggs per day. The 

 low records of 1915 may have been due to the extremely hot, dry 

 weather prevailing during the period when most of the observations 

 were made. 



OVIPOSITION PERIOD. 



The oviposition period of 122 females was observed during 1915. 

 The results are shown in Table XVIII. 



Table XVIII. — Oviposition period of the boll weevil on cotton squares. 





Season. 



Number 



of 

 females. 





Period. 



- 



Source of weevils. 



Maxi- 

 mum. 



Mini- 

 mum. 



Average. 





May- June 



20 

 25 



13 

 5 

 19 

 10 

 12 

 18 



65 



74 

 40 

 74 

 59 

 48 

 68 



1 



15 



19 

 7 



19 



10 

 6 



20 



34.5 



Hibernated grandis unfertilized in 

 spring. 



June-August 



40.0 



June-September 



do 



50.0 





22.6 



Hibernated th urberiae 



do 



41.79 



First generation th urberiae 



July-September 



June-September 



do 



31.4 



Male thurberiae and female grandis 



Male grandis and female th urberiae 



26.0 

 44.3 





May-September. . . 





Total 



122 





Weighted average 







38.2 



Maximum 







77 



i" 





Minimum . . 



















The table shows that the oviposition period ranged from 1 to 77 

 days, with an average of 38.2 days for all females. The first genera- 

 tion grandis had the longest average period and the second generation 

 grandis the lowest. There is no great difference between the length 

 of the oviposition periods of grandis and thurberiae. 



A series of 8 thurberiae females on cotton bolls averaged 25.5 days, 

 with a maximum of 59 days and a minimum of 1 day, while a series 

 of 11 grandis females on cotton bolls averaged 29 days, with a maxi- 

 mum of 61 days and a minimum of 6 days. 



Observations of 32 females on cotton squares at Tallulah in 1914 

 showed an average oviposition period of 34.4 days, a maximum period 

 of 80 days and a minimum period of 10 days. The average oviposi- 

 tion at Tallulah in 1910 was 34.44 days, and the average period in 

 Texas in 1913 was 35.8 days. All records of female oviposition 

 periods average several days less than the 1915 record of 38.2 days 

 at Tallulah. Thus it is seen that if there is any tendency toward a 

 change in the length of the oviposition period of the weevil it is in 

 the nature of an increase rather than a decrease. 



