1908] 



Biological Notes on Potato Beetle 



165 



length of this period for normal beetles as 30 days*, but these 

 figures are given on the supposition that there are but two genera- 

 tions which reproduce, the hibernated generation and the first 

 generation (lb, p. 243). An average of 32 days for the period 

 of oviposition is obtained for the three generations, providing 

 that Pair No. 2 of generation I is ignored, there having been no 

 amount of reproduction with this pair. I should think it fairer, 

 however, to consider averages for each generation, as the condi- 

 tions are different with each, and especially so with the hiber- 

 nated pairs which have a decided advantage in regard to available 

 time for reproduction. It is apparent from previous tables that 

 the period of oviposition is not directly dependent upon the length 

 of life of the adults ; that is to say, the latter may be much greater 

 than the former w^hich does not necessarily close with the death 

 of the female. The reproductive periods appear to be more direct- 

 ly dependent upon the available food supply, the season of growth 

 of the food plant, and similar factors, and I believe the short 

 periods of the later generations may be thus explained, a view 

 in direct conflict with Tower's (1906) limiting physiological 

 principle. 



TABLE Vni. Length of the Period of Oviposition, Different Generations, 1907. 



3. Mating. With each generation, I have recorded the 

 number of times which I ha\'e observed mating, but undoubtedly 

 this act took place with more frequency than the records indicate, 

 as I was unable to watch the pairs continuously, either during 

 the day or night, and they are by no means complete. I tabulate 

 these observations for convenience. 



Pairs were observed mating twice on the same day (Pair No. 

 2, hibernated indi\-iduals), usuallv once in the morninsf and once 



* For special races, however, as shown by the quotations from correspondence 

 in foregoing, the period was much hunger. 



