32 PAPEKS ON THE COTTON BOLL WEEVIL, ETC. 



on June 22, but the number would have been comparatively small 

 and the end of the generation was probably considerably later, so 

 that an increase of ten times, or 1.000 per cent, would be a conserva- 

 tive estimate. The largest number of weevils at College Station early 

 in July was found on Eckol's cotton, which was planted very early, 

 on July 14, 1904, when there were 27 weevils to 100 stalks. This field 

 was adjoining a gin and 1 mile away, on Ayer's cotton, there were but 

 15 weevils to 100 stalks. On the same date, on the Brazos River, there 

 were but 10 weevils to 100 stalks, and on our experimental plats, 

 where the stalks were destroyed the previous fall, the hibernated 

 brood had numbered barely 1 weevil to 100 stalks. There were but 

 3.3 weevils of the first brood to 100 stalks. Accurate figures for the 

 rate of increase from the first to the second brood are not available, 

 but from general observations and from reports of the injury done by 

 the second brood, as compared with the first, it is safe to assert that 

 the rate of increase is not materially greater for the second brood than 

 for the first. The rate of increase of the third brood seems to be 

 decidedly greater, but, as the late-developing individuals of the second 

 brood and the first of the third brood more or less overlap, it is diffi- x 

 cult to determine this accurately in the field. However, the total 

 increase at the appearance of the third brood over the number of 

 hibernated individuals can be given in one or two cases. Along the 

 Brazos River, in 1903, there were but 2 weevils to 100 stalks on 

 June 17, and on August 25 47 weevils to 100 stalks, or an increase 

 of twenty-three times between these dates, the collection at the latter 

 date probably representing part of the fourth brood. In 1903, at the 

 college on our experimental plats, there were 5.5 weevils to 100 stalks 

 on August 13 where there were 1.5 on June 18, representing the 

 hibernated brood. The greatest increase we have observed from the 

 hibernated brood until the middle of August was on the plat of 

 the experiment station at the college barn in 1903, where there were 5 

 hibernated weevils to 100 stalks on June 18 and 233 on August 13, or 

 an increase of forty-seven times. From a careful study of the data it 

 seems safe to assert that the usual rate of increase from the second to 

 the third brood is not over ten or fifteen times in this section, as there 

 is usuall} 7 not over 1 weevil to the stalk of cotton until after mid- 

 August. It will be seen, therefore, that tho the theoretical increase 

 of the weevil, based upon a careful study of its habits and the mor- 

 tality as far as can be ascertained, would show an increase of twenty- 

 five times from between the first and second and second and third 

 theoretical broods of 42 days each from June 1 to September 1, as a 

 matter of fact, during the first period mentioned, the increase up to 

 and including the second brood, emerging about the third week in 

 July, is usually considerably less than twenty-five times the hibernated 

 brood — probably not over fifteen times — and that the total increase 



