Legs 25 



by a hinged spine which hangs from the lower edge 

 of the shin (tig. 20 d). Water-insects generally have 

 the front legs much shorter than the other two pairs. 

 In certain Butterflies the front pair are so greatly re- 

 duced as to be quite useless for walking, so that 

 these insects have practically only four legs. The 

 legs of the middle pair undergo, as a rule, less 

 modification than those of the front and hind pairs, 

 but in some "Water-bugs they are the longest and 

 strongest of all the legs. In other water-bugs and 

 in Water-beetles both the middle and hind pairs are 

 flattened and tapering, serving to propel the insect 

 through the water after the manner of oars. The 

 hind legs are generally the longest of all ; in the 

 Grasshoppers and Locusts they are excessively long 

 and powerful, enabling the insects to spring high 

 into the air. The hind-legs of Bees are specially 

 modified for the collection and carrying of pollen, 

 by the broadening of the shin and the first tarsal 

 segment. The feathered hairs (fig. 20 c) on the body 

 entangle pollen grains which are brushed out by the 

 rows of hairs on the inner face of the wide tarsal 

 segment (fig. 20 b, g). The pollen is then combed 

 out by the bristles (fig. 20 a) on the hind edge of the 

 shin, and stored in the " basket " formed by the 

 hollow on the outer face of the shin in conjunction 

 with the curved hairs on its front margin. The 

 broad sharp edges at the junction of shin and foot 

 (fig. 20 a, h) serve as pincers for cutting wax. In 

 Gnats (fig. 9) and Crane-flies all the legs are long and 

 slender as compared with the body, while in some 

 degenerate female insects they are greatly reduced 

 and very feeble j in extreme cases of degeneration, 

 the female bee-parasites for example, they are alto- 

 gether wanting. 



Many insects which walk with their tarsal seg- 



