IIOMOPTERA 403 



doubtless grown out of the fact that formerly the froth was called 

 "frog-spittle" and was supposed to have been voided by tree-frogs 

 from their mouths. The name is not, however, inappropriate, for 

 the broad and depressed form of our more common species is somewhat 

 like that of a frog. 



The origin and formation of the froth of spittle-insects has been 

 discussed by many writers. Guilbeau ('08) found by many experi- 

 ments that the froth is derived from two sources. The greater part 

 of the fluid is voided from the anus; to this fluid is added a mucilagi- 

 nous substance which renders it viscous and causes the retention of 

 air bubbles, which are introduced into it by the insect by means of its 

 caudal appendages. The mucilaginous substance is the excretion of 

 large hypodermal glands, which are in the pleural region of the 

 seventh and eighth abdominal segments. These are known as the 

 glands of Batelli; they open through numerous minute pores in the 

 cuticula. 



It is evident that the covering of froth protects the spittle-insects 

 from parasites and other enemies. 



In this family the antennas are inserted in front of and between 

 the eyes; the prothorax is not prolonged back of the abdomen, as in 

 the Membracidas ; the tibise are armed with one or two 

 stout teeth, and the tip is crowned with short, stout 

 spines, as shown in Figure 468. 



The Cercopidas is represented in our fauna by six 

 genera, which include twenty-five species. The follow- Fig. 468.-1,5- 

 ing species will serve as examples. p y r m a 



One of the more common and very widely distribut- ^^^^ ''^nlin- 

 ed species is Lepyronia quadranguldris (Fig. 468). The ral size, and 

 adult of this species is a brownish insect, densely one tibia en- 

 covered with microscopic hairs, and black beneath; larged. 

 the hemelytra are marked with two oblique brown bands, which 

 are confluent near the middle of the costal margin; the humeral 

 region is dusky; and the tip of each hemelytron is marked with a 

 small blackish curve; the ocelli are black, but indistinct. This 

 species measures from 6 mm. to 8 mm. in length. 



Somewhat resembling the preceding species, and also common 

 and widely distributed, is Aphrophora quadranotdta. In this species 

 the body is pale; the hemelytra are dusky, each with two large hya- 

 line costal spots, margined with dark brown ; the ocelli are blood-red ; 

 and the head and pronotimi are furnished with a slightly elevated, 

 median, longitudinal line. 



To the genus Clastopiera belong certain other common members 

 of this family. In this genus the body is short and plump, some- 

 times nearly hemispherical; the species are small, our common forms 

 ranging from 3 mm. to 6 mm. in length. Clastopiera proteus is a 

 conspicuous species on account of its bright yellow markings. It 

 varies greatly in color and markings; but the most striking forms 

 are black, with three transverse yellow bands, two on the head and 

 one on the thorax, and with the scutellum and a large oblique band 



