

33 



Among 3tt eggs kept for from 9 to 15 days at a temperature of from 



42 to 15° F. none hatched when later removed to a higher temperature. 



It may be noted here that drying of the square will also retard 



embryonic development, but this condition does not occur in the field. 



Table IV. — Range in duration of egg stage. 





Number 



Duration of 



Number 



Duration of 



of eggs. 



egg stage. 



of eggs. 



egg stage. 





Bays. 





Days. 



2 



2 



4 



5 to 6 



132 



2 to 3 



3 



8 to 9 



192 



1 3 

 \ 2 to 4 



5 



10 to 11 



15 



10 to 12 



42 



3 to 4 



4 



10 to 13 



96 



3 to 5 



3 



13 to 14 



2 



13 to 15 



40 



4 to 5 







13 



1 5 



t 4 to 6 







The duration of the egg stage in bolls does not appear to differ 

 greatty from that in squares. 



HATCHING. 



While still within the egg the larva can be seen to work its mandi- 

 bles vigorousty, 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 membranes having been found in only a few cases. 



HATCHING OF EGGS LAID OUTSIDE.' 



It occasionally happens that a female is unable to force an egg into 

 the puncture prepared to receive it and the egg is left on the out- 

 side of the square or boll (PL III, fig. 9). Eggs so placed usually 

 shrivel and dry up within a short time. To test the possibility of a 

 larva making its way into a square from the outside, a number were 

 protected from drying. Of the 19 eggs tested, 6 hatched in from 2 to 

 3 da} T s. 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 is of no importance,* since the larvse must perish without 

 doing any damage. 



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. Re- 

 peated observations have shown that unfertilized females normally 

 16780— No. 51—05 3 



