Table 5 



Development of the ovaries of 60—70 days 

 old P. chrysocephala at short and long photoperiods. 



Table 6 



Influence of photoperiod ion egg deposition of P. chrycocephala 



(free after Bonnemaison, 1954). 



*) photoperiod between 12 June — 22 ^A.ugust. At the 22nd of August the photoperiod 

 is between 15—16 hours. 



Conclusions 



In the above mentioned experiments no influence of the photoperiod was 

 found on С assimilis and the spring race of С yleurostigma which 11ал"е both 

 a diapause from August to April and oviposite in May and June. 



The two other species with autumnal oviposition habits and aestivation 

 under the conditions of moderate latitudes were of the short-day type. It seems 

 possible that among other insects with autumnal oviposition habits more 

 short day insects can be found. 



The spring race and the autumnal race of C. pleurostigma mainly differ in their 

 responses towards the photoperiod. The spring race being indifferent and the 

 autumnal race being a short day insect. 



Acknoivledgments 



I am indebted to the Netherlands Organization fot the Advancement 

 of Pure Science (Z. W. O.) for a grant in aid to visit the Symposium on the 

 Development of Insects and to Mr. S. C. Bhargava, student at the Agricultural 

 "university of Wageningen, for his care in some of the observations. 



281 



