MIMICRY 



343 



coloured so as to harmonize more or less perfectly with their 

 surroundings. 



If it is advantageous for a noxious species to advertize its true 

 character, it is no less so for an innocuous one to advertize a 

 false character, and gain credit for some power of making itself 

 objectionable which it does not really possess. The practice of 

 bluffing is by no means an exclusively human institution. Thus 

 we find many insects, which in themselves are quite inoffensive, 

 taking on the characteristic warning colouration of dangerous 

 species. The drone-fly mimics the bee, and though they belong 

 to widely different orders of insects, 

 the one having only two wings and the 

 other four, the resemblance is so close 

 as to have given rise, as we saw in an 

 earlier chapter, to the ancient belief 

 in the spontaneous generation of bees 

 from the carcases of oxen (on which, of 

 course, drone-flies had deposited their 

 eggs). 



Most moths, as is well known, have 

 opaque wings, covered with microscopic 

 scales, but in the clear-winged moths 

 (Fig. 175, A) the wings have partially 

 lost their scales and become transparent, 

 and this anomalous feature, combined 

 with the colouration of the body, enables 

 these perfectly harmless insects to mimic 

 the dangerous hornets (Fig. 175, B). 

 Even a harmless snake may mimic 

 the warning colouration of a venomous 

 species, and thus secure for itself the respect which is properly 

 due only to the latter. 



It is not necessary that an animal should be capable of 

 inflicting serious injury upon its enemies when attacked for it to 

 secure immunity from pursuit as soon as recognized. Many 

 butterflies and other insects, which are probably merely distasteful 

 or nauseous (or perhaps actually unwholesome) to birds, exhibit 

 aposematic or warning colouration. Amongst these we find 

 curious associations known as synaposematic groups, the 

 members of which, belonging to distinct species and often by 

 no means closely related to one another, seem to have combined 



B. 



FlG. 175. A., a clear- 

 winged Moth (Sesia cra- 

 broniformis) mimicking 

 B., a .Hornet (Vespa 

 crdbro] ; both X f . (From 

 a photograph.) 



