NATUKE OF THE DAMAGE. 35 
The male scales are more numerous on the leaves than the females. 
The infested leaves turn purplish brown. 
The San Jose scale was formerly supposed to differ from all others 
in the peculiar reddening" effect which it produces upon the skin of the 
fruit and of tender twigs. This, however, sometimes occurs with other 
scales, but is a particularly characteristic feature of this insect, and 
renders it easy to distinguish. The encircling band of reddish dis- 
coloration around the margin of each female scale is very noticeable 
n ^ g ^ t - ^ , Aqs^ 
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Fig. 2.— Appearance of San Jose scale (Aspidiotus perniciosus) on 
bark: a, infested twig, natural size; 5, bark as it appears under 
hand lens, showing scales in various stages of development and 
young larva?. (From Howard and Marlatt.) 
on fruit, especiall} 7 pears. This appearance, however, sometimes so 
closely resembles the small spots on fruit produced by a common fungus, 
fflitomosporium maculattom Lev., as to require close examination with 
a lens to distinguish it. Fruit severeh T attacked becomes distorted, 
rough, and pitted, frequentl} 7 cracking, and ma} r eventually fall prema- 
turely or at least become unmarketable. 
The cambium layer of } T oung twigs where the scales are massed 
together is usually stained deep red or purplish, and when the scale is 
only scatteringly present the distinctive purplish ring surrounding each 
