THE ORIGIN AND FORMATION OF THE FROTH 

 IN SPITTLE-INSECTS 1 



BRAXTON H. GUILBEAU 



During the summer months one observes upon trees, 

 shrubs, herbs and grasses, numerous masses of froth- 

 like material, which resemble large drops of spittle. An 

 examination of a frothy mass soon discloses the presence 

 of a small insect, greenish, brownish, or whitish in color, 

 depending upon the species under observation. This is 

 the immature nymphal stage of an insect belonging to 

 the homopterous family Cercopidas. So far as it is 

 known, all the members of this family surround them- 

 selves with such a secretion, in which they spend their 

 nymphal life. I have had under observation three 

 species, Aphrophora parallela Say, Lepyronia quad- 

 rangularis Say, and Clastoptera proteus Fitch. Each of 

 the species studied in this locality makes a characteristic 

 froth, as may be easily recognized by a little study. 



While there is much which has been written upon the 

 production of froth by the insects of this group, the opin- 

 ions of the many writers are very much at variance. This 

 is especially true regarding the more recent literature on 

 the subject. For this reason it seemed desirable to un- 

 dertake a detailed study of this subject and to determine 

 what organ or organs were concerned in the production 

 of this secretion. This study consisted not only of field 

 observations and laboratory experiments, but of a de- 

 tailed study of the histological structures concerned. 



This work was carried on in the Entomological Labo- 

 ratory of Cornell University, and to its director, Pro- 

 fessor J. H. Comstock, I am indebted for many courtesies. 

 The problem was suggested by Dr. W. A. Riley, and to 

 him I am indebted for constant aid and advice. 



1 Contribution from the Entomological Laboratory of Cornell University. 

 783 



