64 



THE MEXICAN COTTON-BOLL WEEVIL. 



Ds4YS 

 5 /O /S 



HATCHING. 



Wliile still within the egg the larva can be seen to work its man- 

 dibles vigorously, and although a larva has never been seen in the act 

 of making the rupture which allows it to escape from the egg, it is 

 believed that the rupture is first started by the mandibles. The 

 larvae do not seem to eat the membranes from which they have 



escaped, but owing to the extreme delicacy 

 of the skin it is almost impossible to find 

 any trace of it after the larva has left it 

 and begun feeding on the square, the mem- 

 branes having been found in only a few 

 cases. 



HATCHING OF EGGS LAID OUTSIDE OF 

 COTTON FRUIT. 



It occasionally happens that a female is 

 unable to force an egg into the puncture 

 prepared to receive it, and the egg is laid 

 on the outside of the square or boll. Eggs 

 so placed usually shrivel and dry up within 

 a short time. To test the possibility of a 

 larva making its way into the square from 

 the outside a number were protected from 

 drying. Of the 19 eggs tested, 6 hatched 

 in from two to three days. In no case, 

 however, was the young larva able to make its way into the square, 

 and it soon perished. The hatching of eggs laid outside, therefore, 

 appears to be of no importance, since the larva? must perish without 

 doing any damage. 



On August 23, 1906, Mr. R. A. Cushman observed the hatching 

 of two larvae under water from eggs which had been submerged over 

 24 hours. 



Fig. 8. — Diagram illustrating relation- 

 ship of temperature to the egg pe- 

 riod of the boll weevil and showing 

 variations due to humidity. (Orig- 

 inal.) 



EATING OF EGGS DEPOSITED OUTSIDE. 



The number of eggs left outside increases as the female becomes 

 weakened and is especially noticeable shortly before her death. 

 Repeated observations have shown that unfertilized females generally 

 deposit their eggs on the outside, and only occasionally is an infertile 

 egg deposited normally, though the attempt is regularly made to do 

 so. The number of such eggs which may be found is greatly decreased 

 by a peculiar habit observed many times, which will be described. 

 Occasionally it appeared that the puncture which the female had 

 made for the reception of an egg was too narrow to receive it, and 

 after a prolonged attempt to force it down the female, would with- 

 draw her ovipositor, leaving the egg at the surface. She would then 

 turn immediately and devour the egg. In some cases more than one 

 has been devoured after repeated failures to place them properly in 

 the squares. 



