212 A NATURALIST IN BORNEO 



could I see until a rash movement startled the butterfly, 

 and it darted up from under my very nose and was 

 in full flight again. Elymnias lais has the under side 

 of the wing mottled with brown and white, and when 

 the insect is at rest with the wings closed it is almost 

 impossible to detect it among its inanimate surround- 

 ings. From that day forward I kept a, keen look-out 

 for Elymnias lais, and in course of time I did manage 

 to secure a fair number of specimens, but more than 

 once I was deceived as to the nature of the insect until 

 it was so close to me that I had not time to get my 

 net ready before it was gone ; in fact the critical moment 

 of capture was not seized simply because I failed to 

 recognize the deception quickly enough. Now I see 

 no reason whatever to suppose that the faculties of 

 a trained entomologist on the sharp look-out for a 

 definite species of butterfly are less keen than those 

 of a bird in search of a meal, the constituents of 

 which may be scores of different species of Lepidoptera. 

 Such a bird if it had learnt by repeated experiment 

 that Caduga larissa was bad to eat, would ignore those 

 butterflies when out hunting and, unless particularly 

 sharp-set and keenly on the look-out, would be prone 

 to ignore the mimic too, at any rate at first. But the 

 escape of a few individuals suffices to preserve 

 the race ; no one is so foolish as to suppose that all 

 the individuals of a mimetic species escape destruction, 

 for if this were so there would be no checks on their 

 unbounded increase. 



My observations on this butterfly lead to another 

 consideration. Is it possible to tell a Batesian mimic 

 from a Mullerian mimic ? One or two naturalists 

 spend a good deal of time selecting from the cabinet 



