103 
beginning of elune. The later broods also showed long periods of 
emergence, as indicated below. 
Table XLII. — Dates of emergence of moths. 
Generation. 
Paris, 1904. 
Calvert, 1903. 
April 3 to May 30 
April 5 to June 5. 
Second 
June 20 to Jiilv 10 
June 20 to July 5. 
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 ver}^ definite relation 
between the sum of effective temperatures to which the pupae 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 boll worms which does the greater 
part of the injury to cotton. Alfalfa is also considerably 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. 
