44 



THE MEXICAN COTTON-BOLL WEEVIL. 



raised the activity of the weevils increased up to 105° F. When the 

 temperature reached 95° F. or over the weevils were running up 

 and down the tube. By tilling the cylinder with cold water the 

 temperature was lowered to 86° F., at which point the weevils began to 

 cluster at the top on the cork and were crawling slowly. By the 

 addition of ice in the cylinder the temperature was lowered to 59 F., 

 at which point five weevils were struggling on the bottom of the test 

 tube or clinging to one another, four were clustered on the stopper, 

 while one was slowly crawling downward. At 50° F. six weevils 

 at the bottom showed slight signs of life, and one was crawling 

 slowly. At 45.5° F. slight signs of life were still shown, while at 

 40° F. occasional movements only were noted. When the tempera- 

 ture was raised weevils began crawling as 50° F. was passed, and at 

 64° all had left the bottom and were crawling upward. Some recov- 

 ered more quickly than did others. The temperature was again 

 lowered, this time by the use of salt with ice. All movement ceased 

 at 37° F. The cooling, however, was continued to 33° F., after 

 which it was slowly raised to 42° F., at which point movements began. 



EFFECTS UPON SQUARES AND BOLLS OF FEEDING BY THE BOLL WEEVIL. 



From numerous large, open feeding punctures a square becomes so 

 severely injured that it flares very quickly, often within 24 hours. 

 (See PI. V, c.) Males usually make the largest punctures, which they 

 always leave open while they remain for a day or more working upon 

 the same square. It has been often found that squares thus injured 

 by a male will flare before the weevil leaves it. The time of flaring 

 depends upon the degree of injury and the size of the square. Thus 

 small squares winch receive only a single large feeding puncture in 

 the evening are found widely flared in the morning. On the other 

 hand, large squares which are within a few days of the time of their 

 blooming may receive a number of punctures without showing any 

 noticeable flaring. Frequently a square which has flared widely will 

 be found later to have closed again and to have formed a distorted 

 bloom, and occasionally such squares develop into normal bolls. 

 (See PI. V, e, f.) In squares of medium size a single feeding punc- 

 ture does not usually destroy the square. The destruction of a 

 square by feeding results either from drying or decay which follows 

 the weevil injury. 



Table X. — Destruction of squares by the feeding of the holl weevil. 



Period. 



Juno-July 



August-September. 

 < ictober-November. 



Total 



Weighted averages. . 



Total 

 number of 



squares 

 punctured. 



751 

 426 

 176 



1,353 



Number of 



squares 



with 



feeding 



punctures. 



170 

 183 



74 



Total 

 number of 



feeding 

 punctures. 



335 

 383 

 210 



934 



Average 

 number of 



feeding 

 punctures 

 per square. 



1.9 

 2.0 

 2.9 



2.0 



Average 

 number of 

 days before 



falling. 



5.8 

 4.4 

 15.2 



7.0 



