400 AN INTRODUCTION TO ENTOMOLOGY 



the base of the beak, are twisted so that at this point one lies above 

 the other. The two are fastened together by interlocking grooves 

 and ridges ; and between them is a channel for the passage of the food. 

 Within each of the four setae, there is a lumen (Fig. 466, /, /). 



The hypopharynx is a funnel-shaped, chitinized organ found near 

 the base of the ental surface of the labitmi, at the end of the phar\'nx. 



The nature of the metamorphosis differs to a considerable degree 

 in the different families; in most cases it is gradual, but marked 

 modifications of this type have been developed in the Aleyrodidee 

 and in the Coccidae. 



The members of this order feed on vegetation and to it belong 

 some of our more important insect pests. 



This order includes ten families, which are designated as follows : 



The Cicadas, Family Cicadid^, p. 401. 



The Spittle-insects, Family Cercopid^, p. 402. 



The Tree-hoppers, Family Membracid^, p. 404. 



The Leaf-hoppers, Family Cicadellid^, p. 406. 



The Lantern-fly Family, Family Fulgorid^, p. 408. 



The Jumping Plant-hce, Family Chermid^, p. 410. 



The Typical Aphids, Family Aphidid^, p. 415. 



The Adelgids andthePhylloxerids, Family Phylloxerid^, p. 428. 



The Aleyrodids, Family Aleyrodid^, p. 437. 



The Scale-bugs, Family Coccid^, p. 440. 



TABLE FOR DETERMINING THE FAMILIES OF THE HOMOPTERA 



A. Beak evidently arising from the head; tarsi three- jointed; antennas minute, 

 bristle-Hke. 



B. With three ocelH, and the males with musical organs. Usually large 

 insects, with all the wings entirely membranous, p. 401 Cicadid^ 



BB. Ocelli only two in number or wanting; males without musical organs. 

 C. Antenn-^ inserted on the sides of the cheeks beneath the eyes. p. 408 



FULGORID^ 



CC. Antennae inserted in front of and between the eyes. 

 D. Prothorax not prolonged above the abdomen. 



E. Hind tibiae armed with one or two stout teeth, and the tip crowned 



with short, stout spines, p. 402 Cercopid^ 



EE. Hind tibiae having a row of spines below, p. 4o6.Cicadellid^ 

 DD. Prothorax prolonged into a horn or point above the abdomen, p. 404 



Membracid^ 



AA. Beak apparently arising from between the front legs, or absent ; tarsi one- or 

 two- jointed; antennae usually prominent and threadlike, sometimes 

 wanting. 

 B. Tarsi usually two- jointed; wings when present four in number. 

 C. Wings transparent. 



D. Hind legs fitted for leaping; antennas nine- or ten-jointed, p. 410.. 



Chermid^ 



DD. Legs long an slender, not fitted for leaping; antennas three- to 



seven-jointed. 412 Superfamily Aphidoidea 



CC. Wings opaque, whitish; wings and body covered with a whitish 

 powder, p. 437 Aleyrodids 



