SEASONAL HISTORY. 45 



Table X shows that the number of feeding punctures per square is 



determined by seasonal influences, us is also the average number of 

 days before falling. A comparison of the average time from the 

 date of the attack to the falling of the square shows that squares 

 which are only fed on, fall, as a rule, somewhat more quickly than do 

 squares which only contain larvae and have never been led upon. 

 Flaring takes place more rapidly as the result of feeding injury by 

 the adult than from oviposition and injury from the developing stage. 

 While only one egg is generally laid in a square, it appears from Table 

 X that two feeding punctures are usually made in a square. 



Bolls are quite largely fed upon after infestation has reached its 

 height. Small and tender bolls are often thoroughly riddled by the 

 numerous punctures and fall within a short time. (See PI. VII.) 

 Larger bolls may receive many more punctures but do not fall. 

 In bolls an abnormal woody growth sometimes takes the place of the 

 punctured fiber, and a softening and decay of the seeds often accom- 

 panies this change. One or more locks may be destroyed, while the 

 remainder of the boll develops in perfect condition. 



SUSCEPTIBILITY OF VARIOUS COTTONS.' 



During 1903 and 1904 experiments were conducted at Victoria, 

 Tex., to ascertain the relative susceptibility of several varieties of 

 American Upland, Sea Island, Egyptian, and Cuban cottons. The 

 observations at the laboratory were made by carefully examining 

 the plants, looking into each square, and removing every weevil and 

 infested square found. If there were any distasteful or resistant 

 cotton among these ii would surely be found in this way, and if any 

 variety were especially attractive to the weevils it would be equally 

 apparent. Since infested squares were removed, the accident of 

 association or proximity would not determine the location of the 

 weevils found, but all might be considered as having come to the 

 cotton with equal opportunities to make their choice of food, and 

 accordingly their location has been considered as indicating such 

 choice. The period of observation extended from June to November, 

 except with the Cuban cotton, which was planted late and began to 

 square during the latter part of August. For the purpose of this 

 comparison both the several varieties and the various plats of the 

 American cotton will be considered together, as no evidence of 

 preference was found among them. 



In making a comparison of tin 1 results three elements must be con- 

 sidered for each variety of cotton: First, the number of plants of each 

 variety; second, the number of days during which each kind was 

 under observation; third, the total number of weevils found on each 

 class of cotton. The elements of numbers of plants and time under 

 observation may be expressed by the product of those two factors 

 forming a term which we may call "plant days." The total number 

 of weevils found upon any class of cotton divided by the number of 

 plant days will give the average number of weevils attracted by each 

 plant for each day, and these numbers furnish a means of direct com- 

 parison and show at a glance the average relative attractiveness of 



> The following discussion is extracted, but modified, from Bui. 51, Bureau of Entomology, pp. 61-64. 



