43 THE GAME OF BRITISH EAST AFRICA. 



side of the upper wings, which are so protectively coloured. The other parts of the 

 wings and body, concealed while at rest, may be most gaudily coloured without this 

 being apparent when the insect is at rest. 



Amongst tropical insects even more wonderful imitations of leaves, twigs, bark, 

 etc., are noticeable. As I write now, an exact reproduction of a bit of dead grass 

 stem and seed has just fallen on my paper and remains perfectly motionless. Now 

 it runs across the paper and now remains still again. As I was writing a few days 

 ago I saw the half of a dry seed-pod stir and then start walking into my tent. On 

 examination I found a head, body, and legs attached to the underside of this 

 extraordinary back. 



As to butterflies and moths, considering that these resemblances are only 

 marked in the larva and pupa stages or when the mature insect is at rest (the only 

 time it can hope to pass unobserved), it seems as if these resemblances must be 

 protective in origin and function, and unless a wealth of evidence is brought to bear 

 on the subject proving conclusively that such imitation of their surroundings is of 

 no use to these insects and never has been, it seems safest to assume that their 

 present form has been arrived at by natural selection and survival of those less easily 

 detected by their enemies. It would be difficult to conceive of any other agency 

 which has coloured the parts exposed during rest, to such perfect harmony with their 

 surroundings, while bold and glaring colours run riot in other parts of their bodies. 

 It appears to me, as far as the caterpillar is concerned, that the colours they 

 assume cannot but be beneficial to them in escaping to a certain extent from the 

 observation of enemies. 



It is supposed that even keen-sighted birds, in common with the majority of 

 animals, possess the usual failings with regard to sight ; that is, an inability to detect 

 stationary objects, especially when these objects harmonise with their surroundings. 



One can only assume that man, by virtue of his imagination and greater 

 reasoning power, is more fitted to detect such objects as an explanation of how 

 seldom birds seem to find these protectively coloured insects. 



Accepting the protective theory with regard to insects as explaining many 

 things, there still remain, however, many small points which it is difficult to 

 reconcile with this theory. Why should Nature have been at such pains to render 

 the butterfly and moth, protected during their preliminary stages and while at rest, 

 yet so helpless and at the mercy of enemies when on the wing ? 



If these protective colours are chiefly a means of protection against birds, 

 as is so often stated, the butterfly's aimless flights seem utterly in conflict with 

 the idea of the necessity for these precautionary colours. Once the butterfly leaves 



