SB 
818 
C578 
ENT 
CIRCULAR NO. 19, SECOND SERIES. [2D ED.] 
United States Department of Agriculture, 
DIVISION OF ENTOMOLOGY. 
THE CLOVER MITE. 
(Bryobia pratensis Garman.) 
CHARACTERISTICS AND METHOD OF WORK. 
The subject of this circular is a reddish-brown mite about twice the 
size of the ordinary red mite affecting greenhouse plants. It is about 
three-hundredths of an inch in length, oval, and with remarkably long 
anterior legs. Other structural features, together with the peculiar 
hairs which clothe different parts of the body, are illustrated in the 
accompanying figure, which represents, much enlarged, the full-grown 
mite, viewed from above and from below. 
This mite first came into special prominence as a disagreeable invader 
of dwelling houses about ten years since, but it had been known for a 
number of years earlier as an enemy of various fruit and shade trees 
and forage plants, its occurrence on clover, particularly in the Middle 
States, being indicated in its scientific name, pratensis, and its com- 
mon name of clover mite. It belongs to the family of vegetable- 
feeding mites, Tetranychide, which includes such well-known depre- 
dators as the red spider of greenhouses, already referred to, and the 
six-spotted mite, which is quite troublesome to oranges in Florida. 
In California, where this plant mite is especially mischievous, it has 
been very generally confounded with the red spider, and in probably 
most. of the references to injury to deciduous trees on the Pacific Coast 
by the “red spider’’ the real culprit is the insect under discussion. 
The presence of this mite on foliage, either of clover or trees, causes 
the leaves to yellow, or assume a sickly appearance, as if attacked by 
afungus. On the tender leaves of clover, notably on the upper side, 
the juices are extracted, often over irregular, winding areas, imitat- 
ing in appearance the burrows of certain leaf-mining larve. The 
most notable indication, however, of the presence of the mite is the 
