14 
twigs and small branches, and locate there permanently. In a day or 
two they begin the formation of the scale. The male scale is much 
smaller than the female, elongate, wider behind than in front, and 
little, if any, curved. It is uncommon on apple, but often found on 
other food plants. The winged male insect appears in midsummer. 
There is but one brood a year in the North, but in parts of the South 
there are apparently two broods; the second one hatching about Sep- 
tember 1. The oyster-shell bark-louse is widely distributed and 
attacks a great variety of trees, but is especially partial to apple. 
THE SCURFY BARK-LOUSE. 
(Chionaspis furfurus Fitch—fig. 4.) 
This common orchard scale is readily known by its whitish color and 
ovate form. The adult female scale is rather flat, irregularly ovate in 
outline, with the yellowish exuvium at the apex. The life history is 
similar to that of the oyster-shell 
bark-louse. The eggs are laid in 
the early fall and occupy the 
greater part of the scale. The 
mother dies and the scale re- 
mains on the tree during the 
winter to protect the eggs. The 
young hatch during the latter 
part of May or early in June. 
The male scale, which is often 
very abundant, is much smaller 
than the female, snow-white in 
color, and fully twice as long as 
broad, with nearly parallel sides 
and three keels or ridges. The 
winged male insects issue in Sep- 
tember. There is but one brood in the North, but probably two or 
even three in the South. The scurfy bark-louse is widely distributed 
and occurs on most orchard trees, but chiefly on apple and pear. 
Fic. 4.—Chionaspis furfurus: a, 5, infested twigs; c¢, 
female; d, male. (Howard.) 
Asprpiotus (CrRCULAR OR RoUND SCALES). 
To this genus belongs the most destructive known species, the San 
Jose scale. The other species, however, often cause much damage. 
There is a considerable resemblance among the various species, so 
that it is difficult for any inexperienced person to determine them. 
The final characters that separate species are based on the structure of 
the pygidial plate of the adult female scale. To observe this it is 
necessary that a specimen be boiled in caustic potash and mounted in 
balsam ona glass slide. When this is examined under a microscope 
the lobes, spines, hairs, and sinuations of the margin of the plate 
