300 Report oF THE DEPARTMENT OF ENTOMOLOGY OF THE 
tographic prints and mounted specimens, illustrating the work of 
Eriophyes pyri upon its various host plants. For the determina- 
tion of various species of Gamasidae we are indebted to Dr. L. O. 
Howard, of.the U. S. Bureau of Entomology. 
THE MITES. 
The mites belong to the Acarina which constitutes an order of 
the class Arachnida. Related forms are the true spiders, daddy- 
legs and scorpions. Because of their unattractive appearance and 
habits, and obscure structural characters, they have not been of the 
popular interest that obtains with the insects. To the average per- 
son, they are practically unknown. Nevertheless, they are common 
and abundant. Banks states that about three hundred and fifty 
species are recorded from this country where a thousand or more 
probably exist. A large number of the mites play an important 
role in human economy. Among the more prominent species are 
the cattle tick, the leaf blister-mite, the red mite, and the chicken 
mites, all of which are first class pests. Some of the mites find 
their subsistence upon animals and others thrive upon plants. One 
of the important groups of plant-feeders is the Eriophyidae which 
contains the species mentioned. 
THE ARIOPHY IDA. 
STRUCTURE. 
The mites included in this family are small four-legged animals 
ot a vermiform shape, that are hardly visible to the unaided eye. 
They vary in size according to the species. The female of Eriophyes 
mentharius Can., which is one of the largest known mites, is 310 
microns (one-eightieth of an inch) long, while the female of the 
Eriophyes parvulus Nal., the smallest known species, is 100 microns 
(one two hundred and fiftieth of an inch) long. The body has two 
distinct parts: ‘The anterior which is broad and short, and which 
consists of a head fused with a thorax, and is known as the cephalo- 
thorax; and the posterior or abdomen, which is much longer, and 
is annulated and tapering. 
The head appears as a pointed snout which is bent and directed 
downwards. ‘This contains two minute slender stylets, called man- 
