186 [August, 



EXPERIMENTS ON THE COLOUR-SUSCEPTIBILITY OF 



THE PUPATING LARVA OF A FORI A CRATMGI, AND ON THE 



EDIBILITY OF ITS PUPA BY BIRDS. 



BY r. MEERIPELD, F.E.S. 



This pupa is remarkable for the difference between the markings 

 of the pupal and imaginal wings. The imago has no dark markings 

 on its wings, except that the nervures are darkened, and towards the 

 terminations of these nervures on the outer margin they spread out so 

 as to cause the white colouring between the nervures to terminate in 

 a curve. Ou the pupal wing the nervures are not darkened, but there 

 is a row of black spots stretching obliquely across the fore- wings, with 

 often a few more black spots between them and the base, and on the 

 outer margin there is a row of black spots ; when the markings of 

 the marginal wing, as emergence approaches, begin to show through 

 the pupa-case it is seen that the enlarged dark terminations of the 

 nervures correspond in situation, not with the black marginal spots 

 of the pupal wing, but with the interspaces between these spots. 

 The ground colour of the pupa varies from bright greenish-yellow to 

 whitish-grey, and the black spots on the wing-cases vary greatly in 

 number and in size, in some cases being nearly absent. 



In pupating, the larva, unlike that of Pieris hrassicce, which I can 

 hardly get to pupate on any but a flat surface, prefers a rounded one, 

 such as the twigs of the hawthorn or other tree on which it feeds, and 

 has a tendency to be gregarious, four or five often pupating in very 

 close proximity. From the choice of situation, under the shade and 

 shelter of the foliage they are not much exposed to view, though in a 

 strong light they are very conspicuous, and I do not find that the 

 colour varies greatly according to that of the object against which 

 they pupate. Yellow or orange surroundings tend to the production 

 of the yellow ground colour. As regards this ground colour I find 

 little difference of effect between white and black or dark surround- 

 ings, in all these cases it is very variable inclining rather to grey than 

 yellow ; but as regards the black spotting, there is more of this in 

 those that had black or dark surroundings than in those with yellow, 

 orange, or white surroundings. 



As there appeared little likelihood that the colouring and mark- 

 ings of the pupa of this species would have any protective effect, seeing 

 that under all circumstances it would be a conspicuous object to 

 any enemy approat-hing closely to it, there seemed reason for trying 

 whether it was relished or rejected by insect-eating birds, and Dr. A. 



