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MANUAL OF ZOOLOGY. 



ing fresh slaves. The masters are in this case unable even to 

 feed themselves, and their existence is maintained entirely by 

 the devotion of the slaves. In Formica sanguinea, on the 

 other hand, the number of slaves is much less, and both 

 masters and slaves occupy themselves in performing most of 

 the duties necessary for the community. The masters, how- 

 ever, go alone when on slave-making expeditions ; and in case 

 of a migration, the masters carry the slaves in their mouths. 



A second singular fact in the history of Ants is found in the 

 relations which subsist between them and the Aphides, or 

 Plant-lice. The Aphides secrete, or rather excrete, a peculiar 

 viscid and sweet liquid, by means of a gland which is situated 

 towards the extremity of the abdomen, and communicates with 

 the exterior by two tubular filaments. Ants are extremely fond 

 of this excretion, and it is a well-established fact that the 

 Aphides allow themselves to be milked, as it were, by the Ants. 

 For this purpose the Ant touches and caresses the abdomen 

 of the Aphis with its antennae, whereupon the latter voluntarily 

 exudes a drop of the coveted fluid. Ordinarily the Ants seek 

 the Aphides upon plants ; but it is asserted that in some cases 

 they keep Aphides, much in the same way as human beings 

 keep cows, though this is probably partly imaginary. 



ORDER XI. STREPSIPTERA. Females without wings or feet, 

 parasitic. Males possessing the posterior pair of wings, which 

 are large, membranous, and folded longitudinally like a fan. 

 The anterior pair of wings rudimentary, represented by a pair 

 of singular twisted organs. Jaws abortive. 



ThzStrepsiptera constitute 

 a small order, which includes 

 certain parasites of minute 

 size, found on Bees and 

 other Hymenoptera. The 

 female is a soft vermiform 

 grub, without feet, but with 

 a horny head, which it pro- 

 trudes from between the 

 abdominal segments of its 

 host. The larvae are active, 

 and possess six feet \ whilst 

 the males (fig. 118) are 

 winged, and fly about with 

 great activity. 



ORDER XI. COLEOPTERA. Mouth masticatory, furnished 

 with an upper lip or labrum, two mandibles, two maxillae, with 

 maxillary palpi (generally four-jointed), and a movable lower lip 



Fig. 118. Strepsiptera. Stylops Spencii, 

 greatly magnified (after Westwood). 



