58 THE MEXICAN COTTON-BOLL WEEVIL. 



time, and a corky outgrowth appears above the general surface pJane. 

 This prominence has been termed a "wart." The healing is com- 

 pleted even before the hatching of the egg takes place, and thus both 

 egg and larva partake of the benefit of its production. Occasionally 

 warts develop from feeding punctures, which were small, but the exact 

 conditions under which this takes place have not been determined. 

 Nevertheless, the presence of warts is the most certain external indi- 

 cation of oviposition in squares. In a series of observations they were 

 found to follow oviposition in 84 per cent of the cases. 



TIME REQUIRED TO DEPOSIT AN EGG. 



Careful observations have been made upon the time of egg deposi- 

 tion. As in all other processes of the life history of this insect, the 

 period of egg deposition is influenced by climatic conditions. It was 

 found at Tallulah, La., in the early part of the summer of 1910, that 

 the time required for making the puncture varied from 1 minute and 

 20 seconds to 8 minutes and 27 seconds, with an average of 3 minutes 

 and 36 seconds. On the other hand, at Victoria, Tex., in October, the 

 average time was 5^ minutes, and the range from 1 to 13 minutes. At 

 Tallulah the period for the deposition of the egg and the sealing of the 

 puncture varied from 2 minutes and 45 seconds to 9 minutes and 30 

 seconds, with an average of 4 minutes and 41 seconds. At Victoria 

 the period ranged from 3 to 16 minutes and averaged 1\ minutes. 



STIMULATING EFFECT OF ABUNDANCE OF SQUARES UPON EGG DEPOSITION. 1 



Four actively laying females were confined together upon a few 

 squares from September 22 to October 14, 1902. During this period 

 they laid a total of 227 eggs, or an average of 2.37 eggs per weevil per 

 day. For the next 13 days these same weevils were isolated and 

 supplied with an abundance of squares. During this shorter period 

 they laid 236 eggs, or 4.54 eggs per female daily. 



These figures are the more striking, because the stimulation was 

 plainly shown in spite of the general tendency to lay fewer eggs as the 

 weevils grow older and as the average temperature becomes lower. 



ACTIVITY OF WEEVILS IN DIFFERENT PARTS OF THE DAY. 



Two series of observations have been carried on to determine the 

 hourly activity of the weevils. The experiments at Victoria were 

 conducted in the early part of September, when the temperature 

 was ranging from a little under 70° F. to 95° F. during the day. It 

 was found that there was almost a perfect coincidence between the 

 temperature curve and the curve of the average activity of the 

 females in ovipositing. This is shown hi the accompanying diagram 

 (fig. 5). 



It also appeared that the activity of the weevils began and ceased 

 at about 75° F. Perhaps this indicates that the act of oviposition 

 requires a zero of effective temperature different from that of develop- 

 ment. This would be entirely analogous to conditions in flowers, 

 where it is found that the various functions of the plant are governed 



» Modified from Bulletin 51, Bureau of Entomology, pp. 87, 88. 



