Bugs, Cicadas, Aphids, and Scale-insects 
152 
out. The structural characteristics and life-history of the insect may be 
briefly described as follows: 
There may be seen on infested branches, leaves, or fruit, small, flat, 
grayish, irregularly circular scales of varying size (Figs. 250 and 251), the 
large stones (about inch diameter) being the adult females and the smaller 
ones being the immature individuals 
of both sexes. These circles are thin 
waxen plates, bearing one or more (de¬ 
pending on the age of the individual) 
faintly yellowish concentric inner cir¬ 
cles or plates (the inner one usually 
blackish and like a tiny nipple) which 
are the moulted exuviae of the scale. 
When the plant is badly infested the 
scales lie thickly together, even overlap¬ 
ping, and forming a sort of grayish 
scurf over the smooth bark. By rubbing 
or crushing this scurf a yellowish oily 
liquid issues from the injured bodies. 
If a scale be tipped over with a pin¬ 
point, there will be found underneath 
it a delicate flattened yellowish sac-like 
creature, the insect itself (Fig. 252). 
If adult, this degenerate female will be 
seen (by examination with magnifier) 
to have no distinct head, no eyes nor 
antennas, no wings nor legs. It does have a long, fine, flexible, thread-like 
process projecting from near the center of its under side; this is the suck¬ 
ing proboscis, and serves as a means of attachment to the plant as well 
as the organ of feeding. 
Early in the spring, females which have hibernated under their pro¬ 
tecting armor begin giving birth to living young, and continue doing this 
actively for about six weeks, when they die exhausted. The minute orange- 
yellow young, which have eyes, antennae, and three pairs of legs, crawl out 
from under the scale and run about actively for a few hours over the twigs 
or leaves; then they settle down and each* “slowly works its long bristle¬ 
like sucking-beak through the bark, folds its antennae and legs beneath its 
body and contracts to a nearly circular form. The development of the 
scale begins even before the larva becomes fixed. The secretion starts 
Fig. 251. —The San Jose scale, Aspi- 
diotus perniciosus, females and young, 
on bark of fruit-tree. (From living 
specimens; at left, natural size; at 
right, considerably enlarged.) 
* The following long quotation is made from Howard and Marlatt’s “The San Jose 
Scale ” (Bull. 3, N. S., Div. Ent., U. S. Dept. Agric., 1896). 
