New YoRK AGRICULTURAL EXPERIMENT STATION. 207 
ihe PILE ANDERE ARM TTES.* 
Pee eARROL), HH, FE. HODGKISSMND WJ. SCHOENE: 
SUMMARY. 
This bulletin is a preliminary treatise upon the Eriophyidae, a 
group of plant-inhabiting mites of increasing economic importance, 
in which special attention is given to the species thriving upon the 
apple and the pear. This investigation was undertaken because of 
the appearance of the leaf blister-mite upon apple foliage, and its 
widespread distribution in destructive numbers in the apple orchards 
of Ontario, Orleans, Wayne and Niagara counties. 
In the study of the mites upon apple and pear leaves, five species 
have been recognized, which are Eriophyes malifoliae Parr., 
Enophyes pyri (Pgst.) Nal., Eriophyes pyrt var. variolata Nal., 
Phyllocopies schlechtendah Nal., and Epitrimerus pyri Nal. With 
the exception of the former, which is new, these species were first 
recorded from Europe. Eriophyes pyri (Pgst.) Nal., known as the 
leaf blister-mite, is the most abundant species and is responsible for 
the conspicuous injuries to apple foliage. 
The leaf blister-mite is a small, vermiform, four-legged animal, 
about one one-hundred and twenty-fifth of an inch in length and 
hardly visible to the unaided eye. It hibernates in the buds and 
with the maturing of the bud scales seeks the tender leaves, which 
it punctures, producing light green and reddish pimples. These 
develop into galls or blisters of a blackish or reddish brown color, 
depending on the kind and the variety of fruit. Besides the pear 
and the apple, the mite attacks the service berry, the common 
cotoneaster, the white beam tree, and the mountain ash. It is an 
important pest of the pear in nurseries and of apple and pear 
orchards. 
*A reprint of Bulletin No. 283 
