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. Seale 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... - - perniciosus Comst. 
Scale of adult female not circular, the exuvial spot at oné side of the center; the 
half-grown scales usually paler and without the central nipple surrounded by 
SIE STPSSS SS! TAINS Ses ee, eB ae oe na 
2. Adult female scale dark-colored, about 2™ in diameter; exuvial spot orange 
Oisred Gishucolonedite= sae. cscs eee eS od 1. forbesi, ancylus, and ostreeformis. 
Adult female scale paler, or larger, or with white center......................3. 
3. Seale of adult female about 2™™ in diameter, yellowish or pale brownish, with a 
Whe centerrquite tat: Ol PTape =. 222.5: 2.222... . 22a... uve Comst. 
Scale of the adult female very convex, about 23™™ in diameter, of a uniform drab 
or yellowish-brown color, the exuvial spot showing reddish, but not commonly 
OROTA eon oo bb Sas COGS R Ee SES AOE ea h Seal ee en rapax Comst. 
Seale of the adult female large, nearly 3™™ in diameter, flat, and pale-grayish in 
color; the exuvium reddish or orange -...---.------------ juglans-regiex 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. 
nN 
THE SAN JOSE SCALE. 
( Aspidiotus perniciosus 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 ancy/us, 
Sorbesi, and ostreeformis. 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 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 -lose 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; 
