302. ~=Reporr or THE DEPARTMENT OF ENTOMOLOGY OF THE 
surface and are known as ventral setae. Ventral setae (1) are 
always the longest, ventral setae (2) are usually very short, and 
ventral setae (3) are as a rule longer than (2) and are on the fifth 
or sixth ring from the end of the abdomen. 
LIFE STAGES. 
The eggs of mites are round, elliptical or oval, and have a thin 
delicate chitinous covering. They are whitish or yellowish in color, 
and are quite large compared with the size of the parent. The 
young larvae are similar in appearance to the adults and are dis- 
tinguished from, them only by their smaller size, the less number 
of the setae, and the absence of the external parts of the genital 
organs. The nymph shows a further approach to the adult size and 
a greater development of the genital organs. 
HABITS. 
The Eriophyidae are plant feeders and for the most part confine 
their operations to the buds and leaves. Many mites cause excres- 
ences or galls and other deformities on the parts of the plant at- 
tacked, in which they find their habitation and subsistence, while 
others live as inquilines in the galls of other species or are vagrant, 
showing, with the exception of such forms as the citrus mite and 
peach leaf mite, little or no evidences of their feeding. The 
growths due to the work of mites were divided by Thomas? into 
Acrocecidii and Pleurocecidii. Under the former are included ab- 
normal swelling of the buds and irregular bud growth. To the latter 
belong leaf galls, leaf blisters, folding and rolling of the leaves, 
unnatural coloring and chlorosis of the leaves. These hypertrophies 
of plants puzzled early investigators, who, little understanding the 
work of mites, classified the growths according to their form for 
convenience of reference. Among the more important genera estab- 
lished on this basis were Taphrina, Erineum and Phyllerium for 
abnormal hairy or fuzzy growths, Volvolifex for rolled edges of 
leaves, and Cephaloneon for distinct galls. These terms were com- 
monly employed in the early literature upon mites. 
*Thomas F. Ztschr. Naturw., 42:513. 1873. 
