15 



appear quite distinctly. Thus, the characters that may be used in the 

 field are not final and only comparative, and great care must be exer- 

 cised, especially when only a small amount of material is available, 

 and any doubt can be settled only by sending the material to some 

 competent authority who can mount and microscopically examine the 

 species. 



TABLE OF ASPIDIOTUS. 



1. Scale of adult female circular, with exuvium central, dark-colored, the exuvium 



pale yellowish when dark waxy outer covering is rubbed off; scale not very con- 

 vex, about 2""° in diameter; half-grown scales are nearly black and show a 



central nipple surrounded by one or two depressed rings pernicioms Oomst. 



Scale of adult female not circular, the exuvial spot at one side of the center; the 

 half-grown scales usually paler and without the central nipple surrounded by 

 depressed ring 2. 



2. Adult female scale dark-colored, about 2"™ in diameter; exuvial spot orange 



or reddish colored - ^1- forbesi, ancylus, and ostreieformis. 



Adult female scale paler, or larger, or with white center 3. 



3. Scale of adult female about 2""» in diameter, yellowish or pale brownish, with a 



white center, quite flat; on grape ™a2 Comst. 



Scale of the adult female very convex, about 2J"°"' in diameter, of a uniform drab 



or yellowish-brown color, the exuvial spot showing reddish, but not commonly 



exposed rapaa: Comst. 



Scale of the adult female large, nearly 3°™ in diameter, flat, and pale-grayish in 



color; the exuvium reddish or orange juglans-regiie Comst. 



In identifying scale insects by means of the above table, scales 

 should be examined from bark or fruit as clean as possible, and where 

 the scales are not crowded and have room to normally develop. When 

 thickly massed they lose their characteristic shape and appearance, 

 and on sooty or dirty bark they are discolored and abnormal. 



THE SAN JOSE SCALE. 

 (Aspidiotus pemidosus Comstock— flgs. 5, 6, and 7.) 

 The San Jose scale is known to every orchardist by hearsay, but 

 few however, can diijtinguish it from allied scales, such as ancylm, 

 fmiesi and ostre^formh. On badly infested trees the scale presents 

 the appearance of dark gray, scurfy patches. The individual scale is 

 about 2""" in diameter, usually nearly circular in outlme, of a grayish 

 color with the central darker nipple surrounded by one or more quite 

 distinct yellowish or pale grayish rings. When the scales are crowded 

 the outline is more or less distorted. In none of the allied forms is 

 the adult female scale as nearly circular as in the San Jose scale. 

 When on fruit or young twigs there is often a reddish discoloration 

 around the scale. Putnam's scale and the cherry scale have a brighter 

 Xed exuvium, situate one side of the center. The cherry scale is 

 oC much paler than the San Jose scale. The European fruit scale 

 has an exuvium similar to the San Jose, but lacks the darker nipple.; 



