104 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvm. 



They are attached singly, are nearly spherical in shape, and pale yel- 

 lowish or grayish in color. The eggs are quite large as compared 

 with the mite. The young, at birth, are helpless and without tarsal 

 appendages, but soon molt and obtain them. The mites can move 

 quite swiftly, considering their size, and sometimes they spread over 

 a tree with wonderful rapidity. The anal sucker aids them in holding 

 on to a surface, but not in locomotion. They molt four times, it is 

 said, before becoming adult, but pass through no changes in structure, 

 except the development of the genital apertures. At each molt there 

 is a resting period when the mite is within its old and now loose skin. 

 With the drying up of the food-plant in the fall the mites seek winter 

 quarters within the buds or beneath the bud-scales. Sometimes, 

 doubtless, they winter under pieces of bark. When in a l)ud they 

 l)egin to feed on the leaf, and produce the gall before the bud is fully 

 open. 



The Eriophyidte have usually been supposed to have some affinity 

 with the Sarcoptidte; however, 1 think they show far more relation to 

 the Tarsonemidie and Tyroglyphid*. There is not much diversity of 

 form in the family, and generic classification is based on few and 

 rather simple characters. Quite a number of galls have been collected 

 in the United States, but the mites have not been studied except by 

 Professor Garnian, who described a few species. Several European 

 acarologists have carefully studied these mites in recent years, l)ut the 

 work of Alfred Nalepa, of Linz, has been preeminent. 



The better-known genera maybe separated as follows: 



1. Number of abdominal rings on dorsum and venter nearly equal Eriophyes 



Xuml)er of abdominal rings on venter nearly twice as many as on dorsum 2 



2. Dorsum- with the middle area highly arched 4 



Dorsum of an even curve 3 



o. End piece of abdomen plainly separated Anthocoptes 



End piece of abdomen not plainly separated Plu/llocoples 



4. Some of the dorsal altdominal rings extend backward spine-like on the side 



Oxypleiirltes 

 Dorsal rings not so 5 



5. Dorsum of abdomen with two longitudinal furrows F^ntrimerus 



. Dorsum without furrows Tegonotus 



The species, so far known from the United States, have been 

 referred to Krlophijcs., hut several of the other genera occur here. 



]Most notable- of all our species is the pear-leaf l)lister-mite, 

 Ei-lophyes jnjvi^ an European species whose iutroduction into this 

 country seems to have been accomplished before 1870. It is now 

 widely distributed throughout most of the pear-growing region, and 

 also occurs in Australia. It appears to be more injurious in this 

 countr}^ than in Europe, and in some cases it is so abundant that the 

 tree sheds nearly all its leaves Ijefore the fruit is ripe. The mites 

 pass the winter in the btids, and l)egin to feed before the leaves are 



