ANIMALS WITH JOINTED FEET-THE ARTHROPODS 



239 



Fig. 11-34. The wings of insects are highly modified. 

 Those of the butterflies and moths are covered with 

 scales. Some moths, such as this one, possess long 

 scales that resemble fur. Note the long feather-like 

 antennae and the heavily pigmented eyes. 



insects, such as the moth (Fig. 11-34), have 

 wings which are large and covered with 

 scales, while others, like the beetle (Fig. 

 11-35), have hard anterior wings (elytra) 

 that fold over and protect the soft posterior 

 membranous wings. In the flies the wings 

 have been reduced to two — the anterior 

 pair only. The posterior pair has been re- 

 duced to two short stumps called halteres, 

 which serve as sensory organs to maintain 

 balance during flight. 



The legs may all be the same size and 

 used for walking or running, or they may be 

 modified for jumping, as in the case of the 



Fig. 11-35. The forewings of beetles are hard and with- 

 out veins, and the hindwings are membranous. This 

 is clearly demonstrated in the familiar potato beetle 

 (Leptinotarsa decemlineafa) which is destructive to 

 potatoes as well as other crops throughout the United 

 States and Europe. 



grasshopper. Other modifications include 

 the paddle-like feet for swimming, in 

 aquatic forms (Fig. 11-36), the digging legs 

 for excavating, as in the mole cricket, and 

 the pincer-like legs for grasping prey, as in 

 the praying mantis (Fig. 11-37). Certain 

 insects have large, hairy surfaces on their 

 long legs which make it possible for them to 

 walk on water, where they bend the surface 

 tension without breaking it (Fig. 2-2). 

 Some legs are modified for making a sound, 

 as in the case of the cricket, in which the 

 posterior legs are rubbed against the wings 

 to make the characteristic chirp of this in- 



Fig. 11-36. Aquatic insects are modified in many ways for life in the water. The predaceous diving beetle (Dytiscos) 

 shown here has its hind legs fringed with hair-like bristles which serve to increase the effectiveness of these 

 appendages when used in swimming. As a result, it is an excellent swimmer. The insect also stores reserve air 

 under its wings for use while submerged. 



