114 



The San Josk Scale and its Allies 



First and most important of the scale insects which winter 

 partly or fully grown, and which may be destro^'ed by fumig-ation 



of nursery stock, is a 

 group of four very 

 similar kinds of 

 which the San Jose 

 scale (Fig-. 5) is by 

 tar the most injuri- 

 ous. The others of 

 the group are the 

 Forbes scale (Fig-. 6), 

 the Putnam s c a le , 

 :ind the walnut scale 

 ( Fig-. 7 ) , as men tioned 

 above. Althoug-h 

 these four species can 

 be d is t i n g-u -.shed 

 from one another by 

 the entomological 

 expert with perfect 

 certainty, they are so 

 unusually similar in 

 g-eneral appearance, 

 even under examina- 

 tion by the aid of a 

 g-ood hand-glass, that 

 no reliance can be 



CL 



Fig. 5. The S.\x Jt>s?: Scalk; ,? 



natural size; /', 

 U. S. Dept. 



Atrricullure.i 



placed upon the distinctions of the untrained observer. Indeed 

 the experienced entomologist is often driven, in individual cases, to 

 the compound microscope and to the use of minute characters ex- 

 hibited only by specimens especially prepared for microscopic 

 examination. On the other hand, the four scales of this g"roup 

 mav be recogni/.ed by any one as different and distinct from the 

 other common scales. 



In this San Jose group the point at which the young- scale was 

 evidently first formed and from which it has grown is near the 

 center, and is ^parked by a minute nipple surrounded by a g-roove- 

 like ring-. This mark is not so evident on the older scales, but on 

 the young- it ma}'' be readily seen with an ordinary magnifier. 

 From this starting- point the scale g-rows by additions all around 



