58 
common name suggesting its most conspicuous character. It has, 
indeed, the con\ex, elongate, and more or less bent and irregular 
form of an oyster shell. The female scales (Fig. 61, a, b, c) are 
about an eighth of an inch long, the male scales (Fig. 61, d, e) 
smaller, with a little hinge or flap behind, thru which the winged 
males escape when mature. The scale is usually brown to dark 
l^rown in color, tho occasionally bleached to gray by exposure 
to the winter weather. The eggs of the species hatch in Illinois 
shortly after the time the apple blossoms fall. Each female scale 
has during tiie winter from fifty to a hundred and twenty-five pale 
yellowish eggs beneath it, from which the young emerge during 
the latter part of May or the first of June. A second generation 
occurs in central and southern Illinois early in July. The young 
are able, at first, to crawl about somewhat actively, and it is 
principally by this means that the species is distributed, altho it 
may be conveyed to distant points upon infested nursery stock. 
The scale insect is both larger and more injurious than the scurfy 
scale, and infests also a larger variety of trees and shrubs. Elm, 
poplar, willow, horse-chestnut, lilac, red-twigged dogwood, and 
currant are among those most frequently and seriously injured. 
The treatment for this scale is identical with that described in 
the article for the scurfy scale, just preceding. 
The San Jose Scale 
{Aspidiotus prniiciosits Comst.) 
This notorious and destructive pest is much less injurious to 
ornamental vegetation than to fruit trees and shrubs, but is never- 
theless decidedly harmful to several of the former, particularly to 
those belonging to the family of roses. It is also very injurious to 
the mountain ash, but the Japanese quince {Pyrus japonica) is the 
common shrub most likely to betray its presence. 
It is a circular, grayish or yellowish, scale insect about one- 
sixteenth of an inch in diameter, but slightly convex, and marked 
by a central nipple and one or two surrounding circular ridges. It 
is an inconspicuous object, but is recognizable by the appearance 
which it gives to a badly infested bark (Fig. 62), which it covers 
with dark gray patches of a continuous grayish crust, which exudes, 
when crushed with the finger-nail, an oily, yellowish substance due 
to the pressure on the living insects under the scales. The bark of 
a tree but sparsely infested may be seen, on close examination, to 
be irregularly specked with small circular granules which give it an 
unhealthy look. The surface immediately beneath the living scales 
often shows a reddish discoloration ; and on the leaves and green 
twigs are more conspicuous red blotches which surround the scales. 
