( lxxv ) 



of Euchloe' euphenoides and Zegris eupheme roosting at 

 Granada on plants of Biscutella, the appearance of the insects 

 at rest closely approximating to that of the flower heads. 

 Mr. H. Rowland-Brown observed that he had noted a similar 

 resemblance between a specimen of Pieris napi and the flower 

 of Leucojimim on which it rested for the night. Mr. G. C. 

 Champion said that he had noticed specimens of Gonppteryx 

 rhamni seek the under-sides of bramble leaves. 



Dr. T. A. Chapman said that Col. Yerbury's observation on 

 Euchloe euphenoides resting on the flowers of Biscutella is one 

 that may be often made in the South of France, and few 

 English Entomologists have not observed E. cardamines at 

 rest on Alliaria flowers, or on some Umbellifer that roughly 

 resembles it. These facts seem to give the clue to how the 

 practice of these Criicifer-feedmg Pierids of affecting objects 

 of their own colour for resting arose. In so many of these 

 cases, the food-plant is in flower when the butterfly is on the 

 wing, and in the case of Euchloe the flower head is the 

 place selected for egg-laying. It comes about, then, that the 

 butterflies frequent the flowers of their food-plant, both for the 

 honey they afford and for egg-laying. That it would often 

 happen, therefore, to be the resting-place of the butterfly 

 when overtaken by a sudden failure of sunshine is obvious. 

 Nothing further is needed as a basis for natural selection to 

 gradually accumulate in association, the characters of resting 

 on the flower of the food-plant, and assimilation to it in colour. 



A butterfly, seax-ching for a flower head to rest on, will act 

 of course in the same way as one searching for it for any other 

 purpose, viz., it will discover at a distance an object of the 

 desired colour, and will be able to verify what it really is, 

 only after a close approach. If it wants to suck honey, or to 

 lay an egg, such verification is imperative, and all collectors 

 are familiar with butterflies closely approaching a piece of 

 coloured paper, a dead leaf or other object, and only when 

 quite close discovering that it is not the desired mate, or 

 flower, and at once departing. But if a resting place for the 

 night is desired, such verification is not absolutely essential, 

 and a place must be chosen, so that if after several tries a 

 near approach only produces disappointment, an occasion at 



