42 A BOOK OF INSECTS 



and are then called the lower lip, or labium. All three 

 pairs of modified foot -jaws are hinged to the head, and 

 hang in a kind of semicircle behind the labrum. In 

 motion they work from side to side, like pairs of pincers 

 held vertically, and not from below upwards like our own 

 jaws. When not in use they are all packed closely 

 together, and completely cover the mouth. 



On the inner, or front, side of the labium (or second 

 maxillae) there is a fold in the skin of the mouth which is 

 known as the lingua, or tongue. In the cockroach and 

 many other biting insects the tongue is an insignificant 

 member, but among certain of the higher insects it 

 becomes greatly changed, and is vested with important 

 duties. At its base the ducts of the salivary glands open. 



This description of the mouth-parts of a cockroach 

 will be found to apply, in the main, to all mandibulate or 

 biting insects ; but many insects feed chiefly or entirely 

 by suction. Such an insect is the hive-bee. Its mandibles 

 are small and relatively unimportant. They are used 

 chiefly for kneading and cutting wax when comb-building 

 is in progress. The blades of the first maxilla? are long 

 and broad, forming flexible piercers, their sheaths having 

 disappeared, while their palpi are greatly reduced. But 

 the second maxilla 1 — which are intimately fused to form a 

 kind of elongate plate beneath the mouth — carry long, 

 hairy palpi which serve as feelers. Finally, the tongue 

 has become a long grooved organ, adapted for licking and 

 sucking, which terminates in a small, concave "spoon." 

 The mouth-parts of the bee, excepting the mandibles, are 

 often spoken of collectively as the insect's "tongue," 

 because they can be fitted closely together to perform the 

 office of one elaborate sucking organ. So far as is known, 

 the tongue proper is alone employed when small quantities 

 of fluid are being taken up, but in the presence of abun- 



