THE COLORATION PROBLEM. 127 



secondary genital armatures of Lepidoptera are much better known now 

 than they were, so that it should not be an entirely impossible thing to 

 get an approach to accuracy. (The genitalia, eyes, elytra, and other hard 

 chitinous parts of insects seem to make up the bulk of the excreta of 

 insectivorous birds.) 



There is another method which might produce results : — Sit and 

 watch a nest day in and day out, let numberless others do the same, 

 and if you find caterpillars only are brought, change your nest, because 

 one individual v/ill specialise on a particular caterpillar or caterpillars. 

 For example, ray brother last year was busy for a long time watching 

 a pair of Willow-wrens (P. tmchilus var. eversma)mi) feeding young. 

 They brought almost exclusively Tacniocampa cruda and T. stabilis. I 

 noticed Parns caendeus (the Blue Tit) bringing larvae to a nest, and so 

 far as I could see they seemed to be entirely Cheimatubia brumata and 

 Oporabia dilntata, with a very occasional Hubernia defoliaria. On the 

 other hand a Chiff Chaff (L'hi/Uotiropiis rufus), which my brother 

 watched, seemed to have a great partiality for the brown Hj/bemia 

 larvre. Therefore you Avant an individual that hunts for imagines, and 

 not only a species that does so. Mr. Colthrup doubts if birds look for 

 wings at all, but rather the body. I once again disagree. Mr. Colthrup 

 seems to give his birds credit for a very small amount of intelligence. 

 Will he say that Haeinatopus ostrilenKs (the Oyster-catcher), Tadorna 

 corniita (the Sbelduck), and Lanis an/oitatus (the Herring-gull) look 

 for oysters, cockles, and butterfish ready shelled. Is it not the fact 

 that they look for the shells and prize them open or drop them on a 

 stone to break them ? Does Coccotliraustes cuccothraiistes (the Haw- 

 finch) look for cherrystone kernels and single peas ? Does he not 

 rather look for cherries and peapods, knowing full well by experience 

 that inside is the food he seeks ? Cannot the insectivorous birds 

 be allowed credit for sufficient deductive faculty to enable them to 

 deduce presence of bodies from presence of wings ? Dr. A. G. Butler 

 {ioc. cit.) rightly comments that man is very given to under-estimating 

 the intelligence of the lower creation. (I do not wish to enter into the 

 thorny problem of whether a particular a3tion is a blind response to a 

 stimulus, or a caiefull}- reasoned out line of action, as for the purpose 

 of these theories it does not matter.) A further reason is that later 

 researches would seem to show that a very large portion, if not all, of 

 the complicated actions of man are very much the same kind of 

 responses to stimuli. (See Prof. Poulton's " Darwin and Bergsou on 

 the Interpretation of Evolution," Jledrock, No. 1, April, 1912, pp. 50 

 and 51). 



As to Gnophos obsruraria, if in a secure retreat it is only dislodged 

 with much beating. G. obacuraria much prefers a rabbit hole to rest 

 in to anything else, and it requires some hefty thumps on the ground 

 outside to induce it to rush into the waiting net, and it does not, 

 according to my experience, display that nervousness Mr. Colthrup 

 mentions. 



Now the big Boarmiids, whose coloration is cryptic to a degree, and 

 whose attitudes of rest seem specially adapted to render them still less 

 conspicuous, are very nervous, especially of sudden movement or 

 passing shadows, which rather supports the view that the perfec- 

 tion of colouring is due to stringent weeding out. My experience 

 is limited to Boarmia roboraria, B. consortaria, B. (jeiiniiaria. B. 



