Class Insecta 529 



labium manipulate the food into the buccal cavity and esophagus. This 

 is a generalized type of mouth part construction from which the other 

 more specialized kinds develop. 



The cutting-sponging type of mouth parts is best illustrated by 

 that of the horsefly. In this, both the mandibles and maxillae are 

 modified for cutting and breaking the tough skin of a mammal. The 

 mandibles are modified into long, sharp blades and the maxillae are 

 long and probing, while the labium is spongelike in its development 

 for picking up the blood after the epidermis is cut. From the labium, 

 the blood is carried to the hypopharynx. The hypopharynx together 

 with another structure, the epipharynx, forms a tube. Through this 

 tube, blood is carried to the esophagus by suction. 



The sponging type of mouth parts are found in insects such as 

 the houseflies which are dependent for their food supply on either semi- 

 liquid foods or those that are easily soluble in its salivary secretions. 

 In this type, the mandibles and maxillae do not function and are not 

 prolonged. The hypopharynx, the epipharynx, and the labium are 

 modified into an elongated proboscis whose apex is spongelike. This 

 apex is known as the lobelia and its surface has very small capillary-like 

 channels through which the liquified food is transferred to the central 

 food canal. This food canal is formed by the interlocking of the epi- 

 pharynx and hypopharynx. The tube leads directly to the esophagus. 



The honey bee has the chezving-lapping type of mouth parts, a 

 type which is especially adapted for taking up liquid foods. The man- 

 dible and labrum are scarcely modified from those of the grasshopper 

 and are chiefly used for molding wax, while the maxillae and labium 

 are developed into a number of flattened, elongate structures. One 

 of these, the glossa, is a channeled extensile organ. Closely fitting 

 to the glossa are other elongated flaps formed by the maxillae and labium. 

 This arrangement forms a series of channels down which saliva may 

 flow or the food may be drawn up. The elongate glossa may be thrust 

 deep into a flower to extract the nectar. The exact manner in which 

 liquids pass up these mouth parts is subject to some debate. 



The piercing-sucking type of mouth parts is found in many diverse 

 groups of insects and is especially well adapted to types which must 

 pierce some comparatively heavy material and then suck up the contents 

 thus reached. Economically important forms such as the aphids, leaf- 

 hoppers, scale insects, and cicadas which suck juices from plants as 

 well as the noxious mosquitoes, bedbugs, fleas, and lice all have this type 



