THE DOMINANT INSECT 3 



hairs, flattened and otherwise modified. The hairs of 

 many bees have been planned with a view to pollen- 

 gathering, and are curiously branched or twisted. Still 

 other hairs are stiff and sharply pointed, or hollow, brittle, 

 and filled with poison, like the stinging hairs of a nettle. 

 They constitute an effective chevaux de j'rise which serves 

 to keep enemies at bay. Again, many insects' hairs are 

 end-organs of sense. They pass right through minute 

 pores in the chitinous armour, and their roots are in 

 direct communication with nerves, lfy means of these 

 hairs insects receive impressions from the world around 

 them. They have hairs of touch, hairs of taste, hairs for 

 smelling, and hairs which are thought to serve the sense 

 of hearing. 



The great compound eyes invest the insect's head 

 with a quaint resemblance to a diver's helmet ; but, in 

 addition to these huge orbs, there are often three smaller 

 eyes, far less complex in their structure, arranged in a 

 triangle upon the brow. The head, too, carries a single 

 pair of feelers, or antennae — important sense-organs which 

 vary widely both in form and function. 



The mouth of an insect is equipped with a set of parts 

 which are wonderfully fashioned, in the case of each 

 species, to accord with the method of feeding and the 

 kind of food which is eaten. Moreover, the mouth-parts 

 are often modified in such a way that they become, in 

 effect, highly specialised tools. I shall recur to this matter 

 in a subsequent chapter. For the moment I need only 

 point out that there is one office which the mouth of the 

 insect does not serve — viz. that of respiration. An insect 

 breathes through a number of small holes in its side, 

 called spiracles. The orifice of each spiracle is beset with 

 hairs, which serve to keep out dust ; while just within 

 there is an ingenious little valve which is opened and 



