Chap. 30 



ARTHROPODS INSECTS, SPIDERS, AND ALLIES 



601 



Fig. 30.9. Successful hitchhikers, quick transport and the right landing place. 

 Females of wasp-like insects (Lepidoscelio) that ride about on grasshoppers until 

 the latter lay their eggs. Then they dismount and lay their own eggs on those of 

 the grasshopper in which their larvae develop. (After Brues: Insect Dietary. Cam- 

 bridge, Mass., Harvard University Press, 1946.) 



of eyes, simple (ocelli) and compound, the latter an assemblage of simple eyes. 

 Insects never have but one pair of antennae; in grasshoppers they are primarily 

 feelers. In other insects they may have auditory, olfactory, or respiratory func- 

 tions. 



Grasshoppers have the complete quota of mouth parts typical of insects 

 (Fig. 30.11). Their comparative simplicity is a contrast to the specializations 

 of the blood-sucking equipment of mosquitoes and the nectar-dippers of bees. 

 The exact shape of the jaws of grasshoppers is also well fitted to bite particular 

 plant tissues. Lubber grasshoppers feed upon leaves and have jagged "teeth" 

 that tear and shred. Another species eats seeds that it cuts and chisels (Fig. 

 30.12). The mouth parts include: (1 j the broad upper lip or labrum; (2) 

 a median tonguelike hypopharynx; (3) two heavy biting jaws, the mandibles, 

 so shaped that the teeth interlock; (4) two slender jaws, the maxillae whose 

 several parts include jointed palpi with sensory organs on their tips; and (5) 

 a broad median lower lip, the labium with two jointed palpi that bear 

 sensory organs. The opening of the salivary glands is on the edge of the 

 tongue or hypopharynx. 



Thorax. The thorax, with the legs and wings, holds the chief muscles of 

 locomotion and the nerve centers that control them (Fig. 30.10). It is divided 

 into prothorax, mesothorax, and metathorax. On the dorsal side of the 



