INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



163 



THE OAK SCALE 



Chionaspis quercus Comstock 

 (Fig. 140) 



Description. — This very common scale is often a source of annoyance 

 to horticulturists, and especially gardeners who confuse it with more 

 serious pests. The female scales are rather 

 long, pyriform and dark-gray with yellowish- 

 brown exuviae. The length averages T V inch. 

 The male scales are about half as large, very 

 narrow, tricarinated and snow-white with yel- 

 low exuviae. 



Distribution.— This species is quite common, 

 having been taken by the writer in the south- 

 ern, central and northern parts of the State. 



Food Plants.— The coast live oak, maul oak 

 and white oak have been observed as hosts. 



Control. — Control measures are the same as 

 for the pine-leaf scale and are only to be 

 advised for small parks, where the cost of 

 materials is not an important consideration. 



THE WILLOW SCALE 



Chionaspis salicis-nigrw (Walsh) 



(Aspidiotus salicis-nigrw Walsh) 



(Fig. 141) 



Description.— The scales of the females are 

 quite large, elongated or slightly pyriform, 

 being widest near the middle, and pure white 

 or light gray in color. The dorsum is only 

 slightly convex. The exuviae are yellowish or 

 brownish. The length of the scales varies 

 from -J to ^ inch. The male scales are much 

 smaller, white, with yellow exuviae, faintly tricarinated and widest 

 at the posterior end. 



Life History. — The life history is practically the same as for the 

 pine-leaf scale (Chionaspis pinifolice Fitch). 



Nature of Work.— The scale is a bark feeder and attacks the limbs 

 and smaller twigs. Upon the Ceanothus it works around the base near 

 the ground and often completely kills the bushes. 



Distribution.— This is a very common scale in the central and 

 northern parts of the State, especially in the Sierra Nevada mountains. 



Food Plants.— Deer-brush, red-osier dogwood (Cornus stolonifera), 

 big-leaf maple, poplar, shad-bush (Amelanchier canadensis), tulip- 

 tree and willow are among the food plants of this scale. 



Control. — Oil emulsions are recommended to control this pest. 



Fig. 140. — The oak scale, 

 Chionaspis quercus Comst. 

 Males and females on twigs 

 of the coast live oak. En- 

 larged twice. (Original) 



