i6o 



AN INTRODUCTION TO ENTOMOLOGY. 



bers. The mature lice measure 2 mm. (0.08 inch) in length. They 

 are oval, of a dull whit with dusky legs and antennae, and 



with the body dusted over with a white powder. 



Other species of this sub-family are found on roots of grasM 

 herbaceous plants, and usually accompanied by ants. 



Sub- Family II. Cm KMI SIN.-E.* 



The Chennesinic includes those genera of plant-lice in which the 

 front win^s have only two discoidal veins ; the antenna: are from 

 three- to five-jointed. 



This sub-family is represented by two common genera. Chiniu s 

 and Phylloxera. In Chcrmes the antenna; are five-jointed, while in 

 Phylloxera they are only three-jointed. 



C/tcrmcs. The most common species of this genus is the Tine 

 Blight, Chcrmes pinicorticis. This, in its most conspicuous form, ap- 

 pears as patches of white, flocculent, down-like matter on the smooth 

 bark of young white-pine trees. Beneath these patches of white 

 substance the very minute young lice can be found. The win 

 generation appears in early summer. A closely allied species, L 

 vies abicticolcns, infests the terminal shoots of spruce, producing 

 large swellings. 



Phylloxera. This genus contains many species; one of them, 



Phylloxera vastatri.v. has 

 attracted so much atten- 

 tion by the great extent 

 of its ravages that it is 

 often referred toas//v Phyl- 

 loxera. It is more prop 

 termed the Grape Phyllox- 

 era. \Ve have space for only 

 a brief account of the his- 

 tory of this species. 



The presence of this in- 

 sect is manifested by the 

 vines in two ways: fust, in 

 the case of certain sj 



PCS, there appear upon 

 the lower surface of the 

 leaves fleshy swellings, which are more or less wrinkled and hairy 

 (Fig. 134); these are hollow galls, opening upon the upper sun 



FIG. 134. Leaf of grape with palls oi 

 (From Ri 



* Chermeslnae, Chermes: Arab, ktrmfs, Skt. kriwi, a worm. 



