( 428 ) 



Further Notes on the Eggs of Butterflies. 



A Supplement to C. F. M. Swynnerton's Memoir XIV 

 (p. 317), Experiments on some Carnivorous Insects, etc. 



I HAVE made a point of making coloured drawings of 

 any butterfly eggs that I have been able to obtain, as 

 seen against their usual natural background; for it is only 

 in this way that their relative conspicuousness can be 

 assessed. I had hoped to incorporate these drawings in 

 a plate to be published with this paper; but, although 

 this has proved to be impossible, it is worth repeating 

 that the conspicuousness of many of these eggs relatively 

 to the point of vision of the closely-searching bird is very 

 great indeed. The contrast of the ivory-like eggs of 

 Danaida chrysippus with the commonly quite dark green 

 leaves of the species of Asclepias on which it feeds, and 

 that of other Danaine and Acraeine eggs — bright yellow 

 or whitish and before hatching purpHsh brown — with 

 the leaves of their food-plants is quite marked. This con- 

 spicuousness is furthermore often much enhanced by the 

 eggs being laid many together. To watch an Amauris — 

 slowly, deliberately and with carelessness of attack — 

 laying her eggs one after another on a highly- exposed 

 leaf of Cynanchum, the eggs themselves more or less 

 closely spaced and visible to the observer ten feet away, 

 must convince any one who knows the hurried laying of 

 some other butterflies of the existence of special protection. 

 Eggs of certain species are, of course, laid sometimes 

 on the upper surface, sometimes on the lower, of a leaf, 

 sometimes on the petiole or a twig; and the degree of 

 conspicuousness varies accordingly. An egg laid under a 

 leaf should commonly be fairly visible to searching birds 

 which make a point of minutely examining the undersides 

 of leaves ; but its appearance there, in relative obscurity 

 and seen against the light, is naturally somewhat different 

 from what it would be under other circumstances. Yet it 

 is often conspicuous enough as a darker object than the 

 rest of the leaf, for the under surface generally receives 



TRANS. ENT, SQC. LOND. 1915. — PARTS III, IV. (jUNE) 



