336 



MANUAL OF ZOOLOGY. 



Of this nature are the ovipositors of Ichneumons and other 

 insects, and the sting of Bees and Wasps. In the Earwig 

 (Forficula) these caudal appendages form a pair of forceps ; 

 whilst in many Insects they are in the form of bristles, by 

 which powerful leaps can be effected, as is seen in the Spring- 

 tails (Podurcz). In some insects (as the Mole-cricket and 

 Cockroach), the ninth or tenth abdominal segment carries 

 jointed antenniform appendages, which, though perhaps par- 

 tially or even primarily generative in function, are certainly 

 organs of sense, being connected with smell or hearing. 



The organs about the mouth in Insects are collectively 

 termed the "trophi," or "instrumenta cibaria." Two principal 

 types require consideration namely, the masticatory and the 

 suctorial both types being sometimes modified, and occasion- 

 ally combined. 



In the Masticatory Insects, such as the Beetles (fig. 176, A), 

 the trophi consist of the following parts, from before back- 



\p 



Fig. 176. Organs of the mouth of Insects, enlarged ; (A) of a Beetle (Carabus); (B) of 

 the small Cabbage White Butterfly (Pontia rapee] ; (C) of the Bed-bug (Cimex lectn- 

 larius), the mandibles and maxillae being displaced to one side. / Labrum ; in Man- 

 dible ; mx Maxilla ; mp Maxillary palpus ; la Labium ; Ip Labial palpus ; an Base 

 of one of the antennas. (Fig. B is slightly altered fiom Westwood.) 



ward : i. An upper lip, or " labrum," attached below the 

 front of the head; 2. A pair of biting-jaws, or "mandibles;" 

 3. A pair of chewing-jaws, or "maxillae," provided with one 

 or more pairs of "maxillary palps," or sensory and tactile 

 filaments ; 4. A lower lip, or " labium," composed of a second 

 coalescent pair of maxillae, and also bearing a pair of palpi, 

 the " labial palps." The primitive form of the labium that, 

 namely, of a second pair of maxillae is more or less per- 

 fectly retained by the Orthoptera and some of the Neuroptera. 



