THE RED SPIDER ON COTTON. 13 
cephalothorax to tip of abdomen; relative lengths of segments of 
leg I, coxa 25, trochanter 15, femur 53, patella 23, tibia 30, tarsus 
49; femur almost 4 times as long as thick; tip of tarsus (the onych- 
ium) bearing a claw which is strongly arcuate and 4-cleft to its 
middle. Arising also from the onychium, laterad of base of claw on 
either side is an enlarged process which immediately splits into 2 
nearly straight hairs, each of which bears a capitate tip. These 4 
capitate hairs spread spokelike in the same plane and their relative 
lengths are similar to those of the fingers of the human hand viewed 
from the top. The iocation of bristles near the onychium is not 
constant, varying with the locality, etc., 1, 2, or 3 hairs occurring at 
the point of abrupt enlargement near the tarsal end which reach 
almost to the tips of the capitate hairs, and 2, 3, or 4 hairs occurring 
at a distance from the onychium about twice as great as that of the 
distal hairs. (Pi. III, figs. 13,14.) <A series of measured females 
gave the following dimensions: Length (front of cephalothorax to tip 
of abdomen), 0.424 mm.; width (across posterior margin of cephalo- 
thorax), 0.278 mm.; length of foreleg, 0.325 mm. 
Longevity.—The duration of life of the adult female may be divided 
into two periods—a short period immediately following the deuto- 
nymphal molt during which no eggs are laid, and a rather extended 
ege-laying period, which, as determined by experiments at Batesburg, 
is 18.8 days. Perkins states that in warm, dry weather the female 
begins to oviposit in about 48 hours after the last molt, and that in 
cooler weather egg laying may not begin for several days. Von 
Hanstein (1901) found the preoviposition period of Tetranychus aithaea 
to be eight days or more. Hwing (1914) records the average duration 
of the period previous to egg laying to be three and four-fifths days. 
During this inactive period the female mates, feeds to some extent, 
and exhibits a desire to migrate. 
The adult life, from the last molt to death, as computed from 23 
females, is 12.43 days for the summer season in South Carolina. The 
longest individual record of longevity at Batesburg is 39 days, cover- 
ing a period from September 1 to October 9, most of which was dur- 
ing warm weather. The next longest record was 23 days, covering a 
period from September 1 to September 24, also during warm weather. 
Perkins states that in Vermont the females under favorable conditions 
may live at least three weeks and probably longer. Ewing found the 
average longevity of the female during the early fail in Oregon to be 
214 days. Morgan (1897) claimed that females live only from five to 
seven days after reaching maturity. The virile late-fall female often 
lives five months. Very little is known concerning the longevity of 
the male. 
Color variations.—That red spiders vary in color has been observed 
for a long time. It was observed in the case of the European spe- 
cles, and seems to have been instrumental largely in the formation 
