THE PEACH BUD MITE. 111 
SYSTEMATIC RELATIONSHIPS AND OTHER ECONOMIC SPECIES. 
According to Banks! the family Tarsonemide is a small one of 
much biological and economic importance. There are two sub- 
families, Pediculoidine and Tarsonemine. These soft-bodied mites 
resemble also the Tyroglyphide, though the females differ from 
these and all other mites in the presence between the legs (pairs 1 and 
2) of a prominent clavate organ of uncertain use. Concerning the 
systematic position of the family there has been considerable doubt 
among the students of the Acarina and it has not long held any one 
position. It has been associated with the Oribatide and the Chey- 
letidz, and, according to Berlese, the family constitutes one of the 
principal groups of the order. 
The subfamily Tarsonemine includes but two genera, the species 
differing from those of the other subfamily in that the hind leg of the 
female ends ina long hair. The two genera, Disparipes and Tarsone- 
mus, are represented by a considerable number of species, and many 
species of Tarsonemus are of distinct economic importance. Tar- 
sonemus oryze Targ.-Toz.infests the culms of the rice plant in Italy, 
and produces the malady described by Negri under the name “‘bian- 
chella” (bleaching), which is particularly characterized by the pres- 
ence of numerous very fine threads or fibers thought to be produced 
by this acarid; this thread-spinmning habit is not found, apparently, 
associated with any other species of the genus thus far known. 
An affection of oats in France and Germany caused by Tarsonemus 
spirifec March. has recently been well treated by Dr. Paul Marchal 
and others. The mites inhabit the sheath surrounding the head or 
panicle of the oat plant, preventing proper development, and causing 
the stem to assume a distorted spiral shape, which may push out 
along the side. In other cases the distorted stem is held inclosed in 
the sheath, which becomes fusiform, and these plants are called 
‘‘avoines en cigares.”’ The mites appear early in June and the charac- 
teristic spirals during the second fortnight of the same month; all 
stages, as the egg, larva, and both sexes of the adult being found 
together on the plant. It is not known how this mite passes the 
winter. Marchal suggests the possibility that it may hibernate in a 
very resistant condition in the soil, though evidence to the contrary 
is cited as obtained by M. Guille, who considers it probable that the 
mites migrate in the fall to adjacent wild grasses. The mite also 
lives in wheat, barley, and rye, though oats is the preferred food. 
Excessive dry weather is regarded as favorable to its development. 
1Proc. U. S. Nat. Museum, vol. 28, p. 74, 1893, 
2 La mallatia della bianchella del riso cultivato. Casale, 1873. 
3 L’Acariose des ayoines. Annales de l'Institut National Agronomique, 2d ser., tome 6, fasc. ler, 1907. 
