70 
there to projecting hairs, veins, and the edges of the leaf. Many 
exuviae of the mites are found entangled in this web, and certain 
authors think that the mites molt while on the web, but such is cer- 
tainly not always the case with all species. The mites usually show 
a preference for the under side of the leaf, but in some cases they 
are more abundant on the upper side. Occasionally in the spring they 
attack the opening buds. 
IMPORTANT AMERICAN BIBLIOGRAPHY. 
Riley, C.V. — The six-spotted mite of the orange. — Insect Life, Vol. II. 
Jan. -Feb., 1890, pp. 225-226, 1 fig. 
Riley. C.V. — The six-spotted mite of the orange. — Rept. of Entom.. 
t'. 1881), in Ann. Rept. U. S. Dept. Agric. f. 1889 (1890), pp. 
340-345, 1 plate. 
Haryey, F. L. — The two-spotted mite. — Ann. Rept. Maine Agric. 
Exp. Sta. f. 1892 (1893), pp. 133-144, 1 plate. 
Perkins. G. H. — Report of the Entomologist. — 10th Ann. Rept. Vt. 
Agric. Exp. Sta., 1896-97 (1897), pp. 75-86. 1 plate. 
Morgan, H. A. — Observations on the cotton mite. — Bui. No. 48, La. 
Agric. Exp. Sta., 1897, pp. 130-135. 
TETRANYCHID^a. 
As previously indicated, this family includes a number of genera; 
only a few of them, however, are known as "red spiders." But two 
genera have been observed in material collected in this country as red 
spiders. These two genera are abundantly distinct in many points. 
In Tei/rcmychus the body is subpyriform, in StigmcBm elongate and 
subcylindric, in the former with many long, stiff bristles, in the latter 
provided with only a few short hairs. 
Tetranychus Dufour. Ann. Sci. Nat., XXV, 274, (1832). 
DUtigmatus Donnadieu. Rech. Hist. Tetran., (1875). 
PhytocoptesJ>OTmadieJi. Rech. Hist. Tetran., (1875). 
Hetenmyckm Can. ek Fanz. Acari Ital., (1877). 
Oiigonychus Berlese. Acari dann. piante coltiv., (1886). 
The principal characters lie in the general shape of the body; clothed 
with bristles, with simple, moderate legs— with mandibles having the 
bases flattened and united in a retractile plate, with distal joints ex- 
tremely long and slender, and with a palpus having the penultimate 
joint ending in a claw, while the last joint forms a "thumb" bearing 
one 01 more " lingers. " 
Our species as far as known may be tabulated as follows: 
1. Bristles <>f body arise from prominent tubercles 
Bristles of body do not arise from tubercles 3 
2. Lege of avenge length, apparently two daws at tip ol each tarsus — mytilmpidw 
LegB very slender, one claw, t'< nir-clcft beyond the middle gracMpei 
