103 



beginning of June. The later broods also showed long periods of 

 emergence, as indicated below. 



Table XLII. — Bates of emergence of moths. 



Generation. 



Paris, 1904. 



Calvert, 1903. 



First 



April 3 to May 30 



April 5 to June 5. 

 June 20 to July 5. 



Second . .... 



June 20 to July 10 . 



Third 



July 18 to August 22 



July 20 to August 20. 



Fourth 



August 25 to September 25 



October 1 to October 5 



August 25 to September 20. 



Fifth 









It must be anderstood that these dates are the result of general 

 impressions and observations made on oviposition, larvse, etc., and 

 can not be put forth as exact data. 



It was thought at first that there might be some very definite relation 

 between the sum of efi'ective temperatures to which the pup^e had been 

 subjected during the winter and spring, and the dates of spring emer- 

 gence; but calculations based on Weather Bureau temperature records 

 do not show this. The dates of appearance in the different parts of 

 the State are much closer together than such figures would indicate. 

 It seems, rather, that spring emergence must be determined by the 

 temperature of the soil during a smaller number of consecutive warm 

 days. Our Texas records tend to show that moths begin to come out 

 in the spring about the time that the mean monthly temperature 

 reaches 63° to 65° F. 



PROGRESS OF INFESTATION BY GENERATIONS. 



Once the spring moths are out they soon begin to oviposit, princi- 

 pally on young field corn, it being the most general food plant for 

 the first generation of larvae. These larvae mature in the corn, pupate, 

 and the moths of the second generation emerge in time to oviposit 

 upon the tassels and young ears of the corn in the same fields which 

 supplied food for the first generation. The resulting larvae mature, 

 most of them pupating just as the ears commence to harden. Two 

 weeks later, when the third generation of moths appears, the early 

 corn is well hardened and unfit for oviposition. On this account the 

 near-by cotton fields are chosen by the moths and the eggs of this 

 generation are placed on the cotton plants. The larvae of this gen- 

 eration also attack late corn if it is accessible, much preferring it to 

 cotton. This is the generation of bollworms which does the greater 

 part of the injury to cotton. Alfalfa is also considerabl}^ attacked 

 by this generation, even if it is growing close to corn and cotton. 

 The fourth generation, appearing early in September, attacks espe- 

 cially late cotton, which is still green and bearing squares and 3"oung 

 bolls. Late corn and alfalfa also suffer to a considerable extent from 

 this generation. 



