80 





FIELD OBSERVATIONS. 



For one series of observations 500 infested squares were picked 

 promiscuously in the field between May 28 and June 9, 1903. 



A previous field examination was made about the middle of Septem- 

 ber. 1902, and this furnishes some very interesting comparisons as to 

 the weevil's work upon the squares, especially at the beginning of the 

 infestation and after it had reached its height. To facilitate an easy 

 comparison, the results are arranged in Table XVIII. 



Table XVIII. — General results of observations upon selection of squares. 





d 



o 

 M 

 o 



ta 



m 

 o 

 ■-i 

 id 

 B 



CT 1 

 X 



"3 



Squares with 

 1 egg each. 



Squares with 

 more than 

 1 egg each. 



Squares with 



both egg 



and feeding 



punctures. 



Squares fed 

 on only. 





B 

 PS 



Percentage of 

 all squares 

 receiving 



eggs. 



o 



a 



B 

 5 





o 



s 



1^ 



o 



8 



fcjOcS 

 B §? 



Squares infested in laboratory 

 Oct. 23 to Dec. 2. 1902 



630 



477 



317 



56 



91.7 



79.25 



62.9 



19 

 83 

 33 



3.S 

 20.75 

 37.1 



24 

 50 

 46 



3.8 1 110 17. a 



Squares picked in field May 28" to 

 June 9, 1903 



Squares picked in field Sept. 17 to 

 22, 1902 



500 

 105 



10.0 

 43.8 



no 



16 



20.0 

 15.2 







Total 



1,235 



850 



"84.2 



135 



"is. 4 



120 



9.7 



236 



" 18.3 

















A few obvious conclusions may well be stated here. Throughout 

 the season from one-fifth to one-sixth of the squares injured were 

 destroyed by feeding punctures alone. Within this small portion 

 must be included most of the work of males and also of newly 

 emerged females before they reach sexual maturity. As the weevil 

 injury overtakes the production of squares it becomes increasingly 

 difficult for females to find clean squares, and they are forced to 

 deposit eggs in squares already injured and also to feed upon squares 

 which already contain eggs. These conditions serve to increase most 

 rapidly the proportion of squares containing both egg and feeding 

 punctures. This is still further emphasized by the fact that in June 

 only 30 per cent of all injured squares contained feeding punctures, 

 while in September nearly 60 per cent had been thus injured. When 

 females have access to an abundance of squares, they will deposit 

 more than one egg only in about one-fifth of those in which they ovi- 

 posit, while the proportion of those having both egg and feeding 

 punctures is still smaller. 



The tendencies to keep egg and feeding punctures separate, as well 

 as to deposit only one egg in a square, serve to produce the greatest 

 injury of which the weevils are capable, for two obvious reasons: First, 

 because where several eggs are placed in one square it is rarely the 



