8 THE INSECT WOELD. 



in different ways. Some move their six legs successively, or only 

 two or three at a time without distinction, but never both legs of 

 the same pair together, consequently one step is not the same as 

 another. The walk of insects is sometimes very irregular, espe- 

 cially when the legs are long ; and they often hop rather than 

 walk. Others have one kind of step and walk very regularly. 

 They commence by moving the posterior and anterior legs on the 

 same side and the intermediate ones on the opposite side. The 

 first step made, these legs are put down, and the others raised in 

 their turn to make a second. 



Running does not change the order of the movements, it only 

 makes them quicker very rapid in some species, and surpassing 

 in proportion that of all other animals ; but in others the pace is 

 slow. Some insects rather crawl than walk. 



In swimming, the posterior legs play the principal part. The 

 other legs striking the water upwards or downwards, produce an 

 upward or downward motion. The animal changes its course at 

 will by using the legs on one side only in the same way as one 

 turns a rowing boat with one oar without the aid of the rudder. 

 Swimming differs essentially from walking, for the foot being 

 surrounded by a resisting medium, the legs on both sides are 

 moved at the same time. 



The act of jumping is principally performed by the hind legs. 

 Insects which jump have these legs very largely developed, as in 



the figure (Fig. 9). When about 

 to jump they bring the tibia into 

 contact with the thigh, which is 

 often furnished with a groove to 

 receive it, having on each side a 

 row of spines. The leg then 

 suddenly straightens like a spring, 

 and the foot being placed firmly 

 on the ground, sends the insect 



Fig. 9. Posterior leg of a jumping insect. , .-i T 



into the air and at the same time 



propels forward. The jump is greater in proportion as the leg is 

 longer. 



To speak here in a general manner of the wings of insects 

 would be too vague. We shall speak of them at length in their 



