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 mm in diameter; half-grown scales are nearly black and show a 
central nipple surrounded by one or two depressed rings pernieiosus Comst. 
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 mm in diameter; exuvial spot orange 
or reddish colored A. forbesi, ancylus, and ostreseformis. 
Adult female scale paler, or larger, or with white center 3. 
3. Scale of adult female about 2 mm in diameter, yellowish or pale brownish ,*w T ith a 
white center, quite flat; on grape uvse Comst. 
Scale of the adult female very convex, about 2i u,m in diameter, of a uniform drab 
or yellowish-brown color, the exuvial spot showing reddish, but not commonly 
exposed rapax Comst. 
Scale of the adult female large, nearly 3 mm in diameter, flat, and pale-grayish in 
color; the exuvium reddish or orange juglans-regise 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 pernieiosus Comstock — figs. 5, 6, and 7.) 
The San Jose scale is known to every orchardist by hearsay, but 
few, however, can distinguish it from allied scales, such as ancylus, 
forbesi, and ostreseformis. On badly infested trees the scale presents 
the appearance of dark gray, scurfy patches. The individual scale is 
about 2 mm in diameter, usually nearly circular in outline, 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 
colored exuvium, situate one side of the center. The cherry scale is 
often much paler than the San Jose scale. The European fruit scale 
has an exuvium similar to the San Jose, but lacks the darker nipple; 
