WASPS 



201 



upon the tibia. The finer bristles together constitute a very 

 perfect brush for the removal of the minute specks that may 

 pass between the rake-teeth. At the distal extremity of the 

 tibia of the third leg are two movable spurs, one, the inner, 

 decidedly larger than the other; these are closely beset with 

 brush-and-comb bristles, and overhang a similarly provided 

 shallow depression in the proximal part of the metatarsus. If 

 another leg is placed into the depression, its surface is simul- 

 taneously cleaned all round by the brush and comb of the spurs 

 upon one side and that of the depression on the other. The 

 second pair of legs carries a similar 

 arrangement upon its tibia, but the two 

 spurs are of equal size and join the tibia 

 a little farther back from its extremity. 

 The first pair, on the other hand, has 

 only one spur, and that is joined to its 

 tibia at about one-third of the length of 

 the latter from its lower end ; and further, 

 has no bristles except upon its concave 

 face directed towards the metatarsus, and 

 here, as also in the metatarsal depres- 

 sion, there is an extremely fine comb. 

 This contrivance is used solely for clean- 

 ing the all-important sense organs, the 

 antennae. Similar antenna combs are 

 possessed by ants and bees, and any one of these insects may 

 be seen to make frequent use of the apparatus, especially if con- 

 fined and sprinkled with a little dust. 



Abdomen. The abdomen is composed of six visible segments 

 in the female, but of seven in the male. These are roughly 

 annular in shape, consisting of dorsal and ventral semicircles, 

 and overlap one another so as to be capable of considerable 

 extension or compression, after the manner of a telescope. The 

 first segment is abruptly cut off anteriorly, but the posterior 

 segments gradually taper off, so that the apex of the abdomen 

 is sharply pointed. The segments are decorated with yellow 

 and black markings, whose pattern differs in the several species, 

 and, indeed, is not constant among members of the same species. 



FIG. 73. Front leg of wasp. 

 a, antenna comb ; b, tarsus. 



