Table 3 Egg development in C. pleurostigma transferred from a long to a short photoperiod. 



Table 4 



Development of the ovaries of C. pleur ostigtna. 



take place. This"spontaneoiis" break of diapause does not occur promptly 

 in all beetles, as is shown in the next table. 



3. Psylliodes chrysocephala. This insect was also reared though at a small 

 scale at the photoperiods and temperatures mentioned in the next table. 

 It has the same type of life cycle as the autumnal race of Ceuthorrhynclius 

 'pleurostigma. 



These results seem to indicate that also P. chrysocephala is a short day 

 insect. Beetles reared at a short photoperiod consumed more food and were 

 more active than those reared at a long photoperiod. 



Bonnern ais on (1954) also studied this insect. He reared them at temper- 

 atures and photoperiods mentioned in the next table. 



These results are in accordance w\t\\ my experiments. The long photoperiod 

 of 24 hours seems to prevent egg deposition. Those of 16 hours are still favour- 

 able. Bonnemaison, however, did not interprète his results in this way. 

 He considered high temperature and a low relative humidity as the main 

 factors inducing aestivation. 



280 



