242 



SOME ASPECTS OF ECOLOGY 



to the beetle Necrobia rufipes are noteworthy. Thirteen pairs of 

 this beetle were kept under observation from the times of 

 emergence from their cocoons until they died, the average daily 

 mean temperature being 19-4°. During the whole period the 

 insects were fed entirely upon stale fat bacon, and the average 

 life of the female insects was 136 days with a maximum of 183 

 days. The average number of eggs laid per female was 137, with 

 312 as the maximum. In another experiment 76 pairs of the 

 same species were fed throughout their existence upon migrant 

 larvae of the fly Piophila casei. In twenty selected pairs of this 

 series the average life of the female beetle was 279 days, with a 

 maximum of 409 days. The average number of eggs laid per 

 female was 906, with 2,131 as the maximum. The average daily 

 mean temperature, from readings given by these two authors, 

 works out at about 20-5° during the experiment. It is evident 

 that there is an increase in the duration of the life of the individual 

 amounting to over 100 per cent., but this fact is apparently not 

 solely accountable for the high increase in fecundity recorded. 

 This conclusion is borne out by the fact that one female nourished 

 upon Piophila larvae lived only 121 days, but nevertheless laid 

 576 eggs. 



With reference to oviposition by the Noctuid moth Hadena 

 (Polio) oleracea, Lloyd (1920) has shown that unfed imagines, 

 although prolific, produce a greatly reduced number of eggs as 

 compared with those allowed to feed, the food in this case being 

 broken ripe tomato fruits. Lloyd's results, which, however, are 

 based upon small numbers, are given below. 



Table XII. 



