Chap. 30 



ARTHROPODS INSECTS, SPIDERS, AND ALLIES 



599 



Fig. 30.8. Biting mouth parts in action. Upper, caterpillar shearing a leaf with 

 its cutting jaws (mandibles). Its upper lip (labrum) and the attached piece 

 (clypeus) hang downward at the center. The second pair of jaws (maxillae), the 

 lower lip (labium) and the tongue are hidden. Lower, sucking mouth parts in 

 action. Plant lice feeding, a, finding a place; b, needling in the slender tube, 

 mainly composed of the mandibles and maxillae; c, sucking up the sap. The com- 

 bination of piercing and sucking is the method of feeding in such successful 

 insects as the plant lice, squash bugs, mosquitoes and bed bugs; and sucking is the 

 way of the moths and butterflies. (Courtesy, Matheson: Entomology. Ithaca, N.Y., 

 Comstock Publishing Co., 1944.) 



biting tools are the mandibles hinged to the head at the sides of the mouth and 

 operated by muscles that oppose or separate their tips, a sidewise bite. In the 

 lapping and sucking equipments of insects the mandibles, maxillae, labrum 

 and hypopharynx are stiletto-like blades combined into a beak used for suck- 

 ing sap or blood and other fluids (Fig. 30.8). Houseflies lap up syrup. In stable 

 flies (Stomoxys) the lapping organ has become needlelike and able to pierce 

 the flesh. The long nectar-sucking tube of moths and butterflies consists only 

 of maxillae that fit together and make a tube. Their mandibles and other parts 

 have ceased to develop. No butterfly can bite. 



Representative Insects — Grasshopper and Honeybee 



The Grasshopper 



Grasshoppers are generalized in structure and habits, less so than cock- 

 roaches, but outside of agriculture more attractive in human circles. Gen- 

 eralized insects are comparable to the crows that can both walk and fly, 

 specialized ones to humming birds that can fly but scarcely walk. The ancestors 



