PROCEEDINGS OF THE THIUD ENTOMOLOGICAL MEETING 901 



yellow. At the inner margin of the hind wing is a spot of dull reddish 

 brown. When settled on a flower it keeps its wings fully expanded, 

 slightly dihedrally-up and often in quivering movement. It makes no 

 attempt, in my experie^ice, to hide its red spot by covering it with the 

 hind wings. Hence in this position it is an extremely conspicuous 

 object, and in the absence of other evidence, one would be inclined to 

 suspect that its colour-pattern was meant to serve as a warning to enemies. 



If its colouring is meant as a warning then this butterfly must either 

 be unpalatable or must be regarded as being unpalatable by its enemies. 

 But the frequency with which damaged specimens are seen makes it 

 very uidikely that it bears this character among the birds in Agra. 



On examining the underside of this butterfly facts are found that 

 militate strongly against the idea that its colour-pattern serves as a 

 warning. Underneath, the ground colour is not black but dark brown. 

 Most of the yellow areas are larger than those of the upper siu:face. 

 Hence the general effect is that the colouruig is lighter below than above. 

 It may be suggested that this difference is a compensation for the under- 

 side being in shadow ; such an explanation woidd be satisfactory if the 

 purpose of the colouring was concealment but has very little meaning if, 

 as has been suggested, its purpose is display. Further, the hind-wing, 

 on its underside, possesses six more or less rectangular areas and an eye- 

 spot all of dark ochre-yellow bordered with blue and black. Why, 

 it may be asked, should this butterfly have evolved this elaborate pattern 

 on the underside of its wings where it is invisible to birds when the insect 

 is at rest ? 



Let us now consider the appearance of the insect when in flight. 

 When flying slowly it is conspicuous, perhaps as conspicuous as when 

 settled. But when in fast flight it is extraordinarily difficult to see. 

 It appears to me merely as a grey flash. I have had a good deal of 

 practice in observing insects in flight and I know of no other insect that 

 so completely loses its distinctive appearance when flying fast. I have 

 noticed this peculiarity of P. demoleus both in the present season and last 

 year, I have seen it when I was making no attempt to catch the butter- 

 fly and when therefore my attention was not distracted by movements 

 of the net. 



From the point of view of inconspicuousness when in flight the under- 

 side of the wing of P. rlemoleus is perkaps more important than its upper 

 surface because when disturbed it flies off with gain of height and travels 

 at ten or more feet above the ground. A bird that had swooped down to 

 attack a settled demoleus would therefore, as a rule, be below the escaping 

 insect and would see the underside of its wings perhaps a little more than 

 tj^eir upper surfaces. 



