THE CANADIAN ENTOMOLOGIST 



275 



of this sticky material on its abdomen. Comparing the 33 milli- 

 grams of eggs laid by the latter 25 females with 828 milligrams 

 by the above-mentioned 100 females, we find that in case a moth 

 is able to drag herself through the sticky band and go on up the 

 tree she is not likely to deposit more than 16% as many eggs as 

 she would otherwise have done under normal conditions. The 

 conclusion to be drawn is that even those bands which do not 

 keep the moths away from the lower branches are somewhat 

 effective. 



It was found by isolating individuals that eggs are not all 

 deposited at one time but may be laid in at least four different 

 masses. Almost always sterile eggs appeared bunched together, 

 as if from one female and not a few here and there, mixed with 

 fertile ones. 



In conclusion, we might add one more suggestion gathered 

 from the data on the fertility of eggs, Table IV. It would seem 

 from the consideration of the uniformity which the grand total of 

 'the number of sterile eggs indicates for each succeeding night, 

 when compared with the pronounced dropping off in the total 

 number of eggs laid after the second night, that the sterile females 

 retain their eggs as long as possible, while most of the fertile 

 females oviposit during the first or second nights after emergence. 



Results of similar experiments in other localities would be 

 interesting for comparison. 



Table I. 



MEAN TEMPERATURES (FAHRENHEIT DEGREES). 

 Insectary Office. 1917. 



