INSECTS. 



137 



FIG. 172. Ichneumon-fly, showing 

 mechanism of ovipositor. 



with their ovipositors ; the blades of the latter divide, 

 and the egg is forced through this channel into the 

 wound. An abnormal growth of wood is formed about it, 

 from which in time the perfect insect escapes. 



VALUE. A decoction of certain galls, with sulphate of iron, forms 

 the principal ingredient of ink. 



Ichneumon- Flies 



{Ichneumonidce). These 

 insects (Fig. 172) are re- 

 markable for depositing 

 their eggs in other in- 

 sects, using for the pur- 

 pose a long ovipositor 

 that is protected by a 

 sheath composed of four 

 stylets. Rhyssa persuaso- 



ria bores into solid wood in search of its prey. The 

 larva, a soft, footless grub, feeds upon its host, and when 



about to become a pupa 

 spins a cocoon, from 

 which it escapes in the 

 adult form. 



Ants [Formic aria). 

 The ants, in the opin- 

 ion of Sir John Lub- 

 bock, stand next to man 

 in point of intelligence. 

 They erect wonderful 

 dwellings, store up food, 

 FIG. 173. Ant's head and foot. Head : are agriculturists, keep 



e, e, eyes ; a, a, antennas ; m, m, man- and tend their cattle 

 dibles ; /, /, jaws ; /, tongue. Foot : 



s, spur ; c, s, comb of spur ; Ic, leg- 

 comb. 



{Aphidce), seem to pos- 

 sess a sign-language, go 

 to war in organized bod- 

 ies, and in many ways show remarkable intelligence. The 



