42 



AN INTRODUCTION TO ENTOMOLOGY 



The mouth-parts. — The mouth-parts consist typically of an upper 

 lip, labrum, an under lip, labium, and two pairs of jaws acting hori- 

 zontally between them. The upper jaws are called the mandibles; 



the lower pair, the maxillcB. 

 The maxillae and labium are 

 each furnished with a pair of 

 feelers, called respectively 

 the maxillary palpi, and 

 the labial palpi. There 

 may be also within the 

 mouth one or two tongue- 

 like organs, the epipharynx 

 and the hypopharynx. The 

 mouth-parts of a locust will 

 serve as an example of the 

 typical form of the mouth- 

 parts (Fig. 53). 



The mouth-parts enumer- 

 ated in the preceding paragraph 

 are those commonly recognized 

 in insects; but in certain insects 

 there exist vestiges of a pair of 

 lobes between the mandibles and 

 the maxillae, these are the parag- 

 natha. . 



No set of organs in the 

 body of an insect vary in 

 form to a greater degree than 

 do the mouth-parts. Thus 

 with some the mouth is 

 formed for chewing, while with others it is formed for sucking. 

 Among the chewing insects some are predaceous, and have jaws fitted 

 for seizing and tearing their prey ; others feed upon vegetable matter, 

 and have jaws for chewing this kind of food. Among the sucking 

 insects the butterfly merely sips the nectar from flowers, while the 

 mosquito needs a powerful instrument for piercing its victim. In 

 this chapter the typical form of the mouth-parts as illustrated by the 

 biting insects is described. The various modifications of it presented 

 by the sucking insects are described later, in the discussions of the 

 characters of those insects. 



Fig- 53- — Mouth-parts of a locust: la, lab- 

 rum; md, mandible; mx, maxilla; h, hypo- 

 pharynx; /, labium. 



