37 



mined by the amount of accumulated temperature during their 

 development, and, according to a recent re]:»ort of the Fish Commis- 

 sion, the time of hatching can be predicted or controlled to a con- 

 siderable extent in this way. There can be no doubt that the time 

 of emergence of insects from hibernation and the date upon which 

 they begin oviposition or normal activity is dependent upon certain 

 well-defined physical laws which can be determined only by many 

 careful observations and a judicious interpretation of the data col- 

 lected. It seems to the Avriter that this offers a promising field for 

 entomological investigation and one which may very possibly be of 

 much i^ractical importance in our warfare against insect pests. 



Though a much larger number of weevils survive the winter in 

 southern Texas, the hot dry summers kill the larva^ in the fallen 

 squares so that the rate of increase is slower, and often a good crop 

 is made in spite of them. This shows that the rate of increase and 

 the factors governing the mortality of the summer broods are of 

 importance. 



In the study of an insect pest we must first secure as accurate and 

 elaborate a knowdedge as possible of its life and habits under labora- 

 tory or insectai-y conditions. Then, it seems to me, we must go into 

 the field and ascertain what are the conditions; whether or not our 

 artificial environment has changed the life history, rate of reproduc- 

 tion, etc., and what factors influence these phenomena in the open, 

 rhis is what we have essayed to do in as far as our limited means 

 would permit, assuming, for the most part, the correctness of the 

 most excellent and careful laboratory studies of Messrs. Hunter and 

 Hinds at Victoria. Our method in field work has been to make fre- 

 quent counts of large numbers of plants in the same fields through 

 the season, making note of the number of weevils on each plant and 

 the numbers of squares, bolls, and blooms, and the percentage of these 

 which are perfect, or injured by the Aveevil, and the number of squares 

 fallen as a result of weevil injury. Counts were also made of thou- 

 sands of fallen squares at different times to determine the percentage 

 injured by the weevil and the stage of the insects contained. Of 

 course, as the season advanced we were compelled to examine a 

 smaller number of stalks owing to the size of the plants, but always 

 a sufficient number to gi^e several thousand squares from each plot. 

 In this way hundreds of thousands of plants have been carefully 

 counted and the results tabulated, during the last two years. 



The first three summer broods seem to be fairly well defined, the 

 first occurring during the last half of June, the second about the mid- 

 dle of July, and the third about the second week in August in central 

 Texas. There is an interesting relation between the normal rate of 

 formation of squares on the cotton plant and the increase of the 

 weevil. The rate of formation of squares is so exceedingly variable 



