<4 Annals Entomological Society of America [Vol. IV, 



hence limited or continuous and with sufficient data could be 

 plotted in the same way as other continuous variations. It is 

 of the same nature, apparently, as individual variations in the 

 duration of postembryonic stadia, a matter of common obser- 

 vation and which are not controlled by temperature within 

 certain time limits, nor by food. 



As found previously, the daily average effective temperature 

 increases as the period of embryonic development decreases and 

 conversely. But for equal periods of development as shown in 

 foregoing, equal amounts of temperature were not necessary, 

 as witness lots 1 and 2, 7 and 12 and lots 13 and 21; also lots 

 9, 11 and 19. For a degree of temperature (effective) there 

 appears to be a variable amount of growth or development, 

 which as yet remains unpredictable; it is a specific, or maybe 

 generic, characteristic. 



2. Number of Eggs Deposited. 



The data obtained on this point but serve to confirm what 

 is stated by Girault (1908, p. 157 ff.) in a previous paper and 

 also to increase the maximum number observed to be deposited 

 by several hundred. The data were derived mainly by keeping 

 in confinement three pairs of hibernated beetles captured early 

 in the season while mating in a potato field and one or two pairs 

 of the succeeding generations. The total number of eggs 

 deposited, the rate of deposition and other related points for 

 the pairs of the several generations are brought out in Table II 

 presented herewith. The records fall short of what actually 

 would have been the totals for the generations, as toward the 

 second week in August the adult beetles were much neglected 

 and finally died of starvation. The effect of this lack of nour- 

 ishment on the second generation (or parents of the third gener- 

 ation) was especially noticeable, for although mating occurred 

 freely throughout the different lots, oviposition occurred but 

 once and most of the beetles disappeared into the soil for hiber- 

 nation nearly as soon as their food was discontinued. The 

 results indicate, however, that the first generation of adults are 

 capable of as large an amount of reproduction as are the hibernated 

 beetles and that the second generation of adults (or parents of 

 the third generation) were willing or able to reproduce. 



The three pairs of the hibernated beetles were obtained 

 from a potato field in Urbana captured while mating at 11 



