SCALE-INSECTS, BARK-LICE, MEALY-BUGS. 237 
Chionaspis salicis Linn. (The Willow or Cottonwood Scale). 
The trunk and branches of our cottonwood and willow trees 
often present a whitened appearance, which on closer examina- 
tion is seen to be due to the presence of innumerable very small, 
papery and snow-white scales. These scales are of two forms; 
the female scale is the larger one, and is usually more or less 
pear-shaped, with two small, oval, overlapping, cast skins at the 
apex; that of the male is oblong, and has three strongly marked 
ridges running lengthwise, while it possesses only one larval 
skin. 
* 
Fig. 191.—Chionaspis piniloliz Fitch: Infested leaf, male and female scale. After 
Comstock Diy. of Entomology, Dep. of Agriculture. 
The eggs are laid under the larger and pear-shaped scale, 
during the autumn. In depositing the eggs the body of the 
female gradually shrinks away until nothing is left but a mere 
skin at the apex of the scale. The eggs are purple in color, and 
very small; they hatch about the first of June into small, oval, 
flattened lice, which are very active, and quickly spread over the 
tree upon which they were born, and over such adjoining plants 
