246 MANUAL OF ZOOLOGY. 



of their emergence from the egg, and they do not acquire 

 their special characteristics in consequence of any difference 

 of food or treatment. Both are wingless, and they differ solely 

 in the armature of the head. The duties of the workers are to 

 " build, make covered roads, nurse the young brood from the 

 egg upwards, take care of the king and queen, who are the 

 progenitors of the whole colony, and secure the exit of the 

 males and females when they acquire wings and fly out to 

 pair and disseminate the race/' The duties of the soldiers are 

 to defend the community from all attacks which may be made 

 upon its peace, for which purpose the mandibles are greatly 

 developed. 



It may well be admitted, that in such organised communities 

 as those of the Termites, we have the highest development of 

 Insect-life yet known to us. The principle of the division of 

 labour is carried out to its fullest extent much further, indeed, 

 than is possible amongst human beings since the perfection of 

 the greater number of the individuals which compose the com- 

 munity as organisms is sacrificed in order to secure the ful- 

 filment of the duties which are necessary for the existence and 

 welfare of the whole. Even the task of perpetuating the species, 

 and of giving origin to fresh colonies, is entirely left to one 

 class of the community, the defence and protection of which is 

 the special object and care of the remainder. No higher de- 

 velopment could well be imagined amongst creatures devoid 

 of the higher psychical endowments ; and it is worthy of note 

 that at least three distinct and independent families of Insects 

 have attained to this stage namely, the Termites, the Bees, 

 and the true Ants. 



SUB-CLASS III. HOLOMETABOLA. Metamorphosis complete; 

 the larva, pupa, and imago differing greatly from one another in 

 external appearance. The larva vermiform, and the pupa qui- 

 escent. 



ORDER VII. APHANIPTERA. Wings rudimentary, in the 

 form of plates, situated on the mesothorax and metathorax. 

 Mouth suctorial. Metamorphosis complete. 



This order comprises the Fleas (Pulicidcz), most of which are 

 parasitic upon different animals. The larva of the common 

 Flea is an apodal grub, which in about twelve days spins a 

 cocoon for itself, and becomes a quiescent pupa, from which 

 the imago emerges in about a fortnight more. 



ORDER VIII. DIPTERA. The anterior pair of wings alone 

 developed ; the posterior pair of wings rudimentary, repre- 

 sented by a pair of clubbed filaments, called " halteres," or 

 " balancers " (fig. 87). Mouth suctorial. The metamorphosis 



