ENTOMOLOGY 



apparently purposeless. The mandibles of Onthophagus (D) and many 

 other dung beetles consist chiefly of a flexible lamella, admirably adapted 

 for its special purpose. In Euphoria (Fig. 262), which feeds on pollen 



FIG. 45. Various forms of mandibles. A,Mdanoplus; B, Cicindela; C,Apis; D, Onthoph- 

 agus; E, Chrysopa; F-I, soldier termites (after HAGEN). 



and the juices of fruits, the mandibles, and the other mouth parts as 

 well, are densely clothed with hairs. In the larva of Chrysopa, the inner 

 face of the mandible (Fig. 45, E) has a longitudinal groove against which 

 the maxilla fits to form a canal, through which the blood of plant lice is 



sucked into the cesophagus. In termites (F-I) 

 the mandibles assume curious and often inexpli- 

 cable forms. 



Next in order are the maxilla, or under jaws, 

 which are less powerful than the mandibles and 

 more complex, consisting as they do of several 

 sclerites (Figs. 44, 46). Essentially, the maxilla 

 / consists of three lobes, namely, palpus, galea and 

 lacinia, which are borne by a stipes, and hinged to 

 the skull by means of a cardo. The palpus, always 

 lateral in position, is usually four- or five-jointed 

 and is tactile, olfactory or gustatory in function. 

 The lacinia is commonly provided with teeth or 

 spines. The maxillae supplement the mandibles 

 by holding the food when the latter open, and help 

 to comminute the food. Additional maxillary 

 sclerites, of minor importance, often occur. 



The labium, or under lip, may properly be lik- 

 ened to a united pair of maxillae, for both are formed 

 on the same three-lobed plan. This correspondence 

 is evident in the cockroach, among other generalized insects. Thus, in 

 this insect (Fig. 44) : 



FIG. 46. Maxilla of 

 Harpalus caliginosus, 

 ventral aspect. c, 

 cardo; g, galea; /, 

 lacinia; p, palpus; pf, 

 palpifer; s, stipes; sg, 

 subgalea. 



