IXSECTA. 



161 



primarily connected with reinxiJnutiou, but whicli are often con- 

 verted into weapons of offence and defence. Of this nature are the 

 " ovipositors " of Ichneumons, the stings of Bees and Wasps, and 

 the forceps of the common Earwig. 



The organs of the mouth in insects require a brief consideration, 

 as being in the closest possible relation with their habits and mode 



Vig. 108. — Diagram of the extei'nal anatomy of an Insect : a Head cariying the eyes 

 (o) and antenna:; (("i^i); & Fir.st .segment of the thorax, with the lirst pair of legs ; 

 c Second segment of the thorax, with the second pair of legs and the first jiair of 

 wings ; d Third segment of the thorax, with the third pair of legs and the second 

 pair of wings; e Abdomen, withont linilis, but carrying terminal appendages con- 

 cerned in reproduction ; /Fenuir ; ^ Tibia ; (tt Tarsus. 



of life. Two chief types of mouth are recognisable in insects, termed 

 respectively the " masticatory " and the " suctorial," according as the 

 mouth is fitted for biting and chewing, or simjily for imbibing 

 fluids. The masticatory mouth is seen in perfection in the Beetles, 

 in which the following organs are present (fig. 109, A) : 1. An upiper 

 lip or " labrum " (I), attached below the front of the head. 2. A 

 pair of biting-jaws (m) or " mandibles." 3. A pair of chewing-jaws 

 or " maxillae " (nw) proviiled with jointed filaments, called the 



