162 INVERTEBRATE ANIMALS. 



FIG. 73. The Bed Ant (Myrmica rvfa). a Winged male; 6 "Wingless female. Magnified. 



their custom of "milking" the little Plant-lice has been al- 

 ready mentioned. Another very singular habit of some Ants 

 may be just alluded to their habit, namely, of capturing the 

 pupae of other species of Ants and bringing them up as slaves. 

 The relations, however, between the masters and slaves vary 

 a good deal in different cases. In the case, for instance, of 

 the Russet Ant (Formica rufescens) the masters are so entire- 

 ly dependent upon their slaves that they cannot even feed 

 themselves, and the only work which they perform unassisted 

 is the capturing of fresh slaves. In the Blood-red Ant (For- 

 mica sanguined) , on the other hand, the slaves are much 

 fewer in number, and the masters are much less dependent 

 upon their good offices. In all cases, the slaves exhibit the 

 greatest devotion to their masters, and are invariably taken 

 the greatest care of by their captors. 



ORDER XL STREPSIPTERA (Gr. strepho, 1 twist ; pteron, 

 wing). This is an extremely small order of insects, which 

 merely requires to be mentioned. It includes only certain 

 minute parasites, which are found on bees and other Ily- 

 menoptera. The females are destitute of wings or feet, and 

 are merely soft, worm-like grubs. The males are active, and 

 possess a single pair of large membranous wings. Unlike the 

 Diptera, it is the posterior pair of wings which is present, and 

 the anterior pair is quite rudimentary, and is only represented 

 by curious twisted filaments, from which the name of the 

 order is derived. 



ORDER XII. COLEOPTERA (Gr. Jcoleos, a sheath ; pteron, 

 wing). The twelfth and last order of insects is that of the 

 Coleoptera, including the well-known insects familiar to every 



