236 DifRWINISM chap. 



The most interesting and most conclusive example of 

 warning coloration is, however, furnished by caierpillars, 

 because in this case the facts have been carefully ascertained 

 experimentally by competent observers. In the year 1866, 

 when Mr, Darwin was collecting evidence as to the supposed 

 effect of sexual selection in bringing about the brilliant 

 coloration of the higher animals, he was struck by the fact 

 that many caterpillars have Ijrilliant and conspicuous colours, 

 in the production of which sexual selection could have no 

 place. We have numbers of such caterpillars in this country, 

 and they are characterised not only by their gay colours but 

 by not concealing themselves. Such are the mullein and the 

 gooseberry caterpillars, the larvae of the spurge hawk-moth, of 

 the butt-tip, and many others. Some of these cateri)illars are 

 wonderfully consj^icuous, as in the case of that noticed by 

 Mr. Bates in South America, which was four inches long, 

 banded across with black and yellow, and with bright red 

 head, legs, and tail. Hence it caught the eye of any one who 

 passed by, even at the distance of many yards. 



]\Ir. Darwin asked me to try and suggest some explanation 

 of this coloration ; and, having been recently interested in 

 the question of the warning coloration of butterflies, I 

 suggested that this Avas probably a similar case, — that these 

 conspicuous caterpillars were distasteful to birds and other 

 insect-eating creatures, and that their bright non -protective 

 colours and habit of exposing themselves to view, enaljled 

 their enemies to distinguish them at a glance from the edible 

 kinds and thus learn not to touch them ; for it must be 

 remembered that the bodies of caterpillars while growing 

 are so delicate, that a wound from a bird's beak would be 

 perhaps as fatal as if they were devoured.^ At this time not 

 a single experiment or observation had been made on the 

 subject, but after I had brought the matter before the 

 Entomological Society, two gentlemen, who kept l)irds and 

 other tame animals, undertook to make experiments with a 

 variety of caterpillars. 



Mr. Jenner Weir was the first to experiment with ten 

 species of small birds in his aviary, and he found that none of 

 them would eat the fcjllowing smooth-skinned consi)icuous cater- 

 ^ See Darwiu's Descent of Man, p. 325. 



