ELKM KNTARY ENTOMOLOGY 



is modified according to the food of the insect. Thus, in the grass- 

 hopper and similar insects feeding upon vegetation the mandibles 

 are short, with strong teeth at the tip and behind them a crushing 



or grinding surface. In carnivorous and pre- 

 / dacious insects the mandibles are usually 



II long, slender, and sharply toothed, adapted 



for grasping the prey or tearing flesh. In 

 certain of the Neuroptera, as in the aphis- 

 lion (see page 92), the mandible has a 

 deep groove on the inner surface, through 

 which the juices of the plant-lice are sucked. 

 In soldier ants the mandibles are developed 

 as effective weapons, while in other forms 

 they are otherwise specialized according to 

 the food habits of the insect ; but they are 

 always essentially biting organs. 



Beneath the mandibles are the maxillce^ or 

 under jaws. The 

 maxillae are much 

 more complex, con- 

 sisting of a basal 

 portion (stipes) 

 which is hinged to 

 the head (by the 

 cardo) and which 



bears three lobes, - - the palpus, galea, 

 and lacinia. The palpus is composed 

 of four or five segments, resembles a 

 miniature antenna, and, like it, is a 

 sensory organ. The inner lobes, the 

 lacinia, are usually provided with teeth 

 or spines and aid the mandibles in hold- 

 ing and masticating the food. 



The third pair of mouth-parts have 

 grown together on the median line so as 

 to form a single piece, known as the 

 labium t or underlip. In the embryo this is composed of a pair of 

 appendages similar to the maxillae, and for this reason is sometimes 



FIG. 13. Maxilla of a 

 ground beetle (Harpa- 

 his caligifwsiis), ventral 

 aspect 



c, cardo; g, galea; /, la- 

 cinia ; /, palpus ; //, palpi- 

 fer; s, stipes ; sg, subgalea 

 (After Folsom) 



FIG. 14. Labium of a ground 

 beetle (Harpalits caliginosus}, 

 ventral aspect 



g, united glossae, termed the glos- 

 sa; m, men turn ; /, palpus; pg, 

 palpiger ; /;-, paraglossa ; stn, sub- 

 mentum. The median portion of 

 the labium beyond the mentum is 

 termed the ligula. (After Folsom) 



