December, ' 14] PAKKS: TEMPERATURE AND OVIPOSITION OF PHYTONOMUS 421 



If we take the average number deposited in the 1912 experiments, 

 and figure the rate of multiplication, there will be present at the end 

 of the second generation 65,957 individuals, providing that one half of 

 them are females and one half reach maturity. It is highly probable 

 in the inter-mountain country that much less than one half reach 

 maturity and deposit eggs the following season, since many perish in 

 the immature stages in fields of alfalfa after the removal of the first 

 crop, and many which reach maturity are later carried by the wind 

 into mountains and desert wastes where they must perish for Avant of 

 suitable food. Among the individual beetles used in the 1912 experi- 

 ments, oviposition did not progress uninterrupted throughout the 

 season, but the "resting periods" were of short duration, and in most 

 cases the egg deposition was fairly constant during the greater part 

 of the season. Copulation occurred repeatedly during the entire 

 period of oviposition, and all eggs saved for hatching showed a very 

 small percentage of them to be infertile. 



In the autumn of 1912 beetles which emerged from their cocoons 

 June 10 to 13, deposited eggs in out-door cages the latter half of Octo- 

 ber. This, to all appearances, is the beginning of another generation, 

 later interrupted by the approach of winter, but continued in the 

 spring. Females taken from the fields, during November and Decem- 

 ber, deposited eggs in the laboratory continuously through the winter 

 and spring. Eggs deposited in the autumn of 1911 were killed by the 

 winter temperature, and, so far as known, all eggs deposited in 

 the autumn either perish before hatching or the larvae are killed by the 

 winter, depending upon the weather conditions. 



This represents, so far as known, the first accurate records of the 

 average number of eggs deposited b}^ the alfalfa weevil throughout the 

 growing season, and the direct dependence of the same upon tempera- 

 ture. It would be natural to presume that a higher degree of prolifi- 

 cacy would prevail should the beetles become established in a region 

 having a warmer climate and a longer growing season than character- 

 izes the present area of infestation. 



Acknowledgments are due to Mr. E. J. Vosler, now of the California 

 State Insectary, for his assistance in taking records at times when the 

 writer was away from the laboratory. Also to Mr. G. I. Reeves of the 

 Bureau of Entomology for valuable suggestions in photography. 



