October, 1955 ] 



KNOWLEDGE & SCIENTIFIC NEWS. 



241 



mimicry exist. Keeping still to the Hymenoplcra, 

 which on account of their stings constitute such ad- 

 mirable prototypes for mimicry, we find that several 

 European beetles — such as Emwi liirius. and Truhnis 

 fasciatus — have a striking bee or wasp likeness, 

 especially when on the wing. The well-known "Wasp" 

 beetles, too, of the genus Clytus, are probably to be 

 regarded as instances of mimicry. The most inter- 

 esting case of a beetle mimicking a large Hymenop- 

 terous insect, how^ever, is perhaps that of Esthesis 

 fcrruginca, a representative of the Lflngicornia, from 

 Australia. This species has the orange and black 

 banding so commonly associated with the possession 

 of a poisonous sting. Moreo\er, its elytra have be- 

 come so much shortened as to be quite inconspicuous 

 — a character very rarely seen in the group to which 

 the insect belongs. In this way the wings, whether 

 in use or folded above the abdomen, are fully exposed 

 to view, just as they are in the case of a wasp or a 

 hornet. Of course the beetle has only two flying wings, 

 whereas Hymenopterous insects have four. This, 

 however, is a detail which does not strike the casual 

 observer ; moreover, the wings of the beetle are pro- 

 portionately broad, while there is a lobed portion of the 

 hide margin which has much the appearance of a 

 second pair of wings. 



The above is an exceedingly interesting case of true 

 mimicry ; yet among the Lcpidoptcra we find numerous 

 instances which are still more striking. No butterfly 

 or moth possesses a sting, but many species are ren- 

 dered objectionable to insectivorous creatures on 

 account of their noxious juices ; and such species are 

 commonly found to be warningly coloured. Thus 

 they constitute prototypes for mimicry. There is, 

 for example, a distasteful butterfly common in the 

 Indian region of the Eastern Hemisphere, known as 

 Damns mclanoides, the colour pattern of whose wings 

 is mimicked bv a number of other butterflies belonging 

 to several distinct families, and by at least one moth. 

 The Daiiais has pale wings, striped and bordered with 

 black ; and this design is followed, often with sur- 

 prising accuracy, by its mimics. .\ glance at the ac- 

 companying photographs, which show Danais 

 mclanoides and seven of its mimics, will bring this fact 

 home to the reader. Moreover, he will see that the 

 seven butterflies concerned represent no less than five 

 families, viz., Papilioidfr^ S ymphalidcr, Pieridcr, 

 Elymniida and Salyridn-. 



Not infrequently, a mimicking species differs in an 



extraordinary degree from the typical species of the 

 family to which it belongs. This difference is most 

 striking, perhaps, among some of the South American 

 butterflies — notably the genus Dismnrphta. This 

 g-enus belongs to< the Picrid(F. — a family numbering 

 among its members all our well-known " white " 

 butterflies. Its typical .South .American representa- 

 tives differ comparatively little from their relatives 

 in other parts of the world. But only an entomo- 

 logist of experience would recognise Vnmtrphia or/sc 

 as belonging to the same family. Indeed, it was 

 an actual confusion of such species as this with their 

 pi-otot\pes which suggested to the late Henry Walter 



Bates the train of thought which led ultimately to his 

 suggesting the theory of mimicry. Among the 

 butterflies which he brought home from South America 

 there were species which, in the hurry of collecting, 

 and packing, he had placed together ; but which sub- 

 sequent examination showed to be widely different in 

 structure. 



It may be asked : By what process can this insect 

 {D. irisc) have come to differ so remarkably from the 

 typical members of its family, as to resemble the dis- 

 tasteful type represented by Methoma confusa ? At 

 first thought, natural selection, powerful agent though 

 we know it to be, seems incapable of achieving such a 

 result. But we must remember that we are looking 

 at the work — not of tens or hundreds, but possibly of 



1. Dcinau jiiehin 



2. Papilio epycides. 



3. Painlio mac^veu-:.-i 



4. Papilio xenocUs. 



