218 SPOLIA ZEYLANICA. 



such a dormant period in any Ceylon butterflies). If the females 

 of the February flight lay the eggs for the November flight, 

 presuming they are to hatch in November, the chances are that 

 the heavy rains of S.W. monsoon (May to August) would destroy 

 the majority, leaving few for the November flight, whereas the 

 latter is the more prolific ; but supposing the feeding grounds of 

 the larvae of the latter are in districts not eflEected by S.W. 

 monsoon then it is difficult to understand why they, apparently, 

 do not emerge and form a flight similar to the other two, some- 

 where about Mar>^h, April, or May, but, in Colombo, at any rate, 

 practically no Gatojjsilias are to be seen during the seven or eight 

 months preceding the November flight. I can only arrive at two 

 explanations : - 



(1) The offspring of the February flight must lie in a dormant 

 state during one or other of their stages, for several months ; or 

 (2) the species must breed throughout the year in some favour- 

 able locality as regards food-plant and weather. The reason they 

 do not migrate at regular intervals is most probably due to the 

 habit of their favourite food plant, which is an annual leguminous 

 shrub ; it dies off during the first dry months of the year after 

 shedding its seeds ; these spring up again with the commence- 

 ment of the rains, and about September-October the plant is plen- 

 tiful and vigorous, thus forming ample food supply for immense 

 numbers of the larvae. Their numbers increase so rapidly and 

 to such an extent that the females, prompted by some natural 

 instinct, migrate, followed by males, and seek pastures new 

 whereon to deposit their eggs. Thus the bi-annual migration 

 seems to arise from the abundance of food plant available, which 

 is greatest shortly before the November flight takes place, 

 gradually diminishing as the dry weather approaches. 



The species Gatopsilia chiefly concerned in these flights are 

 Gatopsilia x>omona and its variety crocale, and G. 2Jyranthe with 

 its varieties gnoma^ ilea, and chryseis. G. pomotia was most 

 predominant, but I did not secure a sufficient number during 

 the flight to ascertain which sex was most abundant. In the 

 case of G. pyranthe the males appeared to predominate during 

 the November flight, for out of 100 specimens secured in one 

 day, 87 per cent, were males, althougli towards the end of the flight 

 the remaining stragglers were almost entirely females. In a 

 previous capture during a February flight in Colombo (referred 

 to by Manders) 75 per cent, were females. 



OSWIN S. WICKWAK. 

 Colombo, January 20, 19U6. 



