148 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
Jose scale (Aspidiotus perniciosus Comst.). At one time this species 
was one of the most important shade-tree pests in the United States. 
It is an introduced species, having been imported on fruit-tree stock 
from China. From the point of original establishment in the San 
Jose Valley of California, it has now spread over all of the United 
States and Southern Canada. Although known chiefly as a pest of 
fruit trees, it attacks and seriously affects a considerable number of 
species of shade trees and ornamental shrubs, including elm, mountain 
laurel, redbud, magnolia, and firethorn (Cotoneaster pyracanthd). 
The covering of a full- grown female is approximately 1 mm. in 
diameter, is gray, and bears a dark, central, nipplelike projection. 
The covering of the male is smaller and more elongate. 
There are two to four generations of this species in the Northern 
States, and probably still more in the South. Each female gives birth 
to about 600 living young. If allowed to develop unmolested for 2 to 
3 years on forest and shade trees, it may kill twigs and branches, and 
even entire trees. Infestations on shade trees may be controlled by the 
application of contact sprays (p. 52) (Painter, 325). 
Hemlock, pine. spruce, and fir in the Eastern States are sometimes 
attacked by a small, dark-gray or nearly black, oblong scale known as 
the hemlock scale (4 spidiotus ithacae (Ferris) ). “It is found at- 
tached to the under side of needles of the host trees, and in heavy in- 
festations even on twigs and branches. Injury to trees results from a 
heavy foliage drop. 
The Putnam scale (Aspidiotus ancylus (Putn.)) isa small. circular 
scale about 1 mm. in diameter. It is found over most of the United 
States and attacks several species of trees and shrubs. Females differ 
from those of the San Jose scale in that they are a little darker and 
the nipple, which protrudes slightly from the dorsum, is off center and 
is brick red. Forest trees most susceptible to the Putnam scale are 
basswood, soft maple, poplar, ash, beech, black locust, and hackberry, 
the first two being the most susceptible. Limbs, branches, and at times 
the trunks of these trees are attacked. Injury is seldom great, although 
twigs and branches may be killed. 
There are several other species of Aspidiotus to be found on forest 
and shade trees and they may be listed with their hosts, as follows: A. 
aesculi Johns, horsechestnut; A. comstocki Johns, maple; A. forbest 
Johns, cherry; A. juglans-regiae Comst., the walnut scale, on a wide 
variety of trees and shrubs; A. osborni Newell & CkIl., oak: A. ostre- 
aeformis Curt., the European fruit scale, on willow and poplar: A. 
townsendi Ckll., yellow poplar; A. w/m7 Johns, elm, hackberry, locust, 
and yellow poplar; ; A. californicus Coleman, the black pine leaf scale. 
on various species of pine (fig. 35) and Douglas-fir. The last-named 
species was sufficiently injurious in the Lake States in 1943 to make it 
FIcuRE 35.—Female scales of -tspidiotus californicus on pine needle. About 
20 X natural size. 
