THE ABUNDANCE OF WHITE BUTTERFLIES IN 1917. 



57 



But on August 5th a somewhat remarkable specimen of P. bras- 

 sicae settled at my feet as I sat in the garden. Its peculiarity 

 is that the wing rays, which are traceable as pale yellow lines on 

 parts of the white portions of the wings, are carried through the 

 black tips. I at first thought that the appearance might have 

 been caused by the specimen, which is not a very fresh one, 

 having been rubbed in some way, but various experiments that 

 I have tried on others to obtain a similar appearance have 

 utterly failed to do so. The peculiarity appears to be quite 

 natural to the specimen and much on a par with similar 

 markings so frequent in the black borders of the wings of male 

 Colias edusa (see figure). 



On July 29th I examined some cabbages that were growing 



in an adjacent garden, and found that the backs of the leaves 

 were smothered with the eggs of P. hmssica as thickly as though 

 they had been sprinkled on with a pepper pot. These particular 

 cabbages did not, however, suffer from the resultant larvas, 

 spraying and other preventive measures taken at the right time 

 having saved them ; but other patches in the neighbourhood that 

 were not so treated were soon reduced to a state of skeleton. In 

 some cases that came under my notice nothing was left but bare 

 stalks and leaf ribs, not one bit of the leaf cuticle remaining 

 throughout whole patches. Tropaeolums in the garden were 

 absolutely consumed by the larvjie, the culprit in this being 

 P. rapes. 



No less remarkable than the abundance of the Lepidopteron 

 was the attack upon it by its parasites. Mr. Harwood, of 

 Sudbury, Suffolk, informs me that from large numbers of larvae 

 of P. hrassicce collected in his neighbourhood up to the third 

 week in September not one produced a pupa, all being killed by 



