ISTATUKE 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 I'eddening- effect which it produces upon the skin of the 

 fruit and of tender twigs. This, however, sometimes occurs with other 

 scales, but is a particularl}^ 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 ver}^ noticeable 



n 



CL -4 



Fig. 2.— Appearance of San Jose scale {A&pidiotaa pernicloms) on 

 bark: a, infested twig, natxiral size; 6, bark as it appears under 

 hand lens, showing scales in various stages of developnu>nt and 

 young larvae. (From Howard and Marlatt.) 



on fruit, especially pears. This appearance, however, sometimes so 

 closely resembles the small spots on fruit produced by a common fungus, 

 EnUnnosporiniii maculatu,ni Lev., as to require close examination with 

 a lens to distinguish it. Fruit severely attacked becomes distorted, 

 rough, and pitted, frequently cracking, and may eventually fall prema- 

 turely or at least become unmarketable. 



The cambium layer of young 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 



