THE BOOK OF NATURE STUDY 



With the majority of insects a wasp is not likely to be con- 

 founded ; but inasmuch as there are some beetles, flies, and 

 moths which closely resemble wasps in general shape, and in 

 the arrangement of the yellow and black markings with which 

 the body is decorated, it will be well to indicate the points of 

 difference. Firstly, then, wasps possess a sting ; this weapon 

 is not found in any of the above-named mimics. Further dis- 

 tinctions lie in the characters of the wings. Both front and 

 hind-wings of the wasp are thin, transparent, and membranous ; 

 when in use the two wings of one side are locked together by 

 a series of minute hooks which are situated on the front edge 

 of the hind-wing and become engaged in a grooved ledge upon 

 the hinder border of the front wing ; when at rest the wings 

 are placed parallel and dorsal to the abdomen, and the front 

 wing undergoes one fold along its whole length, so that its posterior 

 half underlies the anterior, and the width of this wing is thereby 

 halved. In beetles the front wing is hard, horny, and opaque, 

 and serves as a cover and protection to the hind-wing, which 

 is the chief instrument of flight ; when at rest the hind-wing 

 is folded in a complicated fashion both longitudinally and trans- 

 versely. Flies possess but one pair of wings (the front) ; these 

 are not folded at all, and generally stand out at an angle from 

 the body, i.e. they are not brought parallel to the abdomen 

 when at rest. The " Clearwing " moths, which resemble wasps, 

 have a dark opaque band along the apex of the wing ; the front 

 and hind wings are not united by hooks, and when at rest there 

 is no folding of either wing. There are, of course, many other 

 structural differences between these insects, but the above will 

 suffice for our purpose. 



It is probable that birds and other insect-eating animals 

 learn by experience that wasps possess a sting which produces 

 painful effects. The conspicuous coloration of the wasps serves 

 as a warning to such animals not to repeat their early experi- 

 ments. Thus yellow-and-black has unpleasant associations, and 

 the harmless beetles, flies, and moths referred to above probably 

 derive advantage and enjoy comparative immunity from attack 

 by passing under the colours of the really dangerous wasp which 

 they mimic. 



