ELEMENTARY 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 

 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 maxilla, 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) anji 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, 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- 

 lus caliginosus}, ventral 

 aspect 



, cardo ; g, galea ; /, la- 

 cinia ; /, palpus ; pf, palpi- 

 f er ; s, stipes ; sg, subgalea 

 (After Folsom) 



FIG. 14. Labium of a ground 



beetle (ffarpalus caliginosus}, 



ventral aspect 



g, united glossae, termed the glos- 

 sa ; m, mentum ; p, palpus ; pg, 

 palpiger ; pr, paraglossa ; sm, sub- 

 mentum. The median portion of 

 the labium beyond the mentum is 

 termed the ligula. (After Folsom) 



