50 THE MEXICAN COTTON-BOLL WEEVIL. 



of 20 days. The conclusion seems plain that so long as leaves alone 

 are fed upon, eggs do not develop, while a diet of squares leads to 

 the development of eggs in about four days. It is worthy of note 

 that the interval between the first feeding upon squares and the depo- 

 sition of the first eggs is almost the same with these weevils taken in 

 middle life as with weevils which have just emerged. 



An examination of hibernated females taken in the spring of 1903, 

 which had fed for six weeks upon cotton leaves, showed that their 

 ovaries were still latent. Copulation was rarely observed among 

 hibernated weevils until after squares had been given them. In a 

 few days after feeding upon squares, mating and oviposition began. 

 The average period was from three to five days, and, having once 

 begun, oviposition continued regularly. 



It has been found that food passes the alimentary canal in less than 

 24 hours. Assimilation therefore must be very rapid. It is evident 

 that while leaves will sustain life certain nutritive elements found 

 only in squares are essential in the production of eggs. 



These experiments were repeated in 1904 with similar results. 



Upon dissecting weevils just taken from hibernation, it was found 

 that females contained no developed eggs, but that their ovaries were 

 in an inactive condition, similar to those of females which had fed for 

 months entirely upon leaves during the previous fall. Upon examin- 

 ing females taken from stubble cotton later in the spring, but before 

 squares nad appeared, it was found that they also were in similar 

 condition. This was also true of females kept in the laboratory from 

 the time of emergence from hibernation until squares became abun- 

 dant, with only leaves for food. It seems peculiar that upon a purely 

 leaf diet eggs are not developed, but all observations made indicate 

 that this is the case. It can not be said definitely whether the females 

 examined had been fertilized, but it is certain that they were not 

 ready to deposit eggs. 



PLACE OF EGG DEPOSITION. 



The location of egg punctures, while variable, still shows some 

 selection on the part of the weevil. This may be due partly to the 

 form of the squares and partly also to the size of the weevil, but what- 

 ever the explanation, the fact remains that in a majority of cases the 

 egg puncture is made on *a line about halfway between the base and 

 the tip of the square. When so placed the egg rests either just inside 

 the base of a petal or among the lowest anthers in the square, accord- 

 ing to the varying thickness of the floral coverings at that point. 

 Punctures are very rarely made below this line, though they are some- 

 times made nearer the tip. Almost invariably the egg puncture is 

 started through the calyx in preference to the more tender portion 

 of the square, where the corolla only would need to be punctured. 

 With bolls no selection of any particular location has been found, 

 but eggs seem to be placed in almost any portion. 



THE ACT OF OVIPOSITION. 



While engaged in making egg punctures, the favorite position of 

 the weevil is with its body parallel to the long axis of the square and its 

 head toward the base. Trie tip of the weevil's body is thus brought 

 near the apex of a medium-sized square. It may be that the position 



