6 
THE COLORADO EXPERIMENT STATION 
parasites, would drop from the trees prematurely. Before spraying 
became generally adopted in the Grand Valley, the products of whole 
pear orchards were rendered unmarketable. 
DESCRIPTION AND LIFE HISTORY. 
This scale belongs to that class of insects receiving their food by 
sucking the juices of the plants to which they are attached. Having 
no mouth parts with which to chew their food, stomach poisons or 
arsenical sprays are without value applied to them. They must be 
controlled by contact sprays. They are of minute size and many 
times when but moderately abundant upon trees escape notice except by 
the trained observer. Every fruit grower should acquaint himself 
with the appearance of the pest and, if possible, be able to distinguish 
it from its nearest relatives. This will not always be possible for the 
average orchardist and it will be advisable to send samples of scale 
insects found upon the trees to the entomologist of the Agricultural 
Experiment Station, for determination. This should be done to avoid 
the mistake of maintaining more dangerous forms of insects which 
might be introduced by chance. The figures of Plate 2 show the 
insect drawn from life, but enlarged, represent its various stages, de¬ 
tails of structure and general appearance and will aid in the deter¬ 
mination of the species. 
The male is the only form bearing wings and it is winged only 
upon becoming adult. All females and the males throughout the 
greater part of the year spend their lives attached and immovable upon 
the bark, leaves or fruit and it is during this time that the damage to the 
host plant is done. It is during this period of their lives that the hard, 
scaly coating forms over them as a protecting covering. The scales are 
secretions from the body of the insect concealed beneath. A short 
period is spent by both sexes crawling over the surface of the tree 
or its fruit before settling down for feeding. This period ,of but a 
few days duration at most, follows the hatching of the young from 
eggs deposited beneath the scales. At this time the very minute 
insects are scattered over the infested bark, appearing to the naked 
eye as mere specks of yellow orange dust. They are much smaller than 
newly born young San Jose scale. For so small an insect they are very 
active. One under observation traversed a distance of one-half inch 
in one minute. When it finally settles down it inserts its beak through 
the epidermis of the plant and, if a female, from that time to its 
death does not move. If a male, it remains stationary through its 
development to the adult and then equipped with wings, comes out 
from beneath its covering for the fertilization of the full grown females 
still beneath their scales. 
When first attaching itself to the bark the secretion of the scaly 
covering commences. The newly settled individuals appear as very 
small white specks, as at that time the white fibers of the secretion have 
not yet become matted together nor assumed the darker hues. The 
female scale in developing assumes a circular outline and lies slightly 
convex upon the surface. Individually when matured, it is of a pale 
