2 BRITISH INSECTS 



question has six legs, a distinction which at once puts 

 crabs, lobsters, spiders, ticks, centipedes, etc., out of 

 c*urt. Here, then, we have a sure foundation upon 

 which our knowledge of insects may be based. But 

 their six-footedness is only one among many characters 

 which serve to separate insects from all other animals. 

 So that before we discuss British insects in detail, we 

 shall do well to consider briefly the peculiarities of 

 insects as a class. 



The name " insect " is derived from the Latin verb 

 insecure (" to cut into "), and is very appropriate, since 

 the typical insect's body is divided into three sections 

 viz., the head, the thorax, and the abdomen. These 

 parts are not always obvious, especially in young 

 insects such as caterpillars and grubs ; but we shall 

 see later that even in these cases the tripartite plan is 

 already sketched out, as it were, and waiting to be 

 revealed when the final stage of the life-history is 

 reached. Each of the three main sections of the 

 insect's body is made up of rings or segments. In the 

 head always, and often in the thorax, these are so 

 intimately fused together that the lines of juncture are 

 practically obliterated ; but in the abdomen most of 

 tke segments can usually be distinguished without 

 difficulty. This segmentation of the body is an im- 

 portant point, because it serves to support the view 

 now held by scientific men that insects have descended 

 from worm-like ancestors creatures whose body was 

 composed of a simple head-lobe followed by a series of 

 nearly identical rings, each of which carried a pair of 

 lcomotor appendages or " feet." This idea, once 

 firmly grasped, explains many details of insect 

 structure that might otherwise prove difficult to com- 

 prehend. It will help us, for instance, to understand 



