THE RED SPIDER ON COTTON. 15 
of considerably ereater length and prominence, the frontal pair not 
over half as long as the subfrontal pair, which, like the median pair next 
behind, are in length equal to two-thirds the greatest width of the body. 
Relatively the legs are longer in the ies than in the female. Tip 
of upper side of third joint of palpi with a short, stout, curved spine. 
The penis (Ewing, 1913) is short, stout, and has a hook at its end 
which turns upward and ends in a flattened barb. A measured 
series of males yielded the following dimensions: Length (anterior 
margin of cephalothorax to tip of abdomen), 0.256 mm.; width, 0.142 
mm.; foreleg, 0.256 mm. 
Color variations.—The color variations of the male are very slight 
compared with those of the female. Nearly all individuals conform 
to one type, which is of an amber-yellow color. 
GENERAL FEATURES. 
Structural varvations.—The microscopic characters of the palpus of 
the red spider (PL. III, figs. 1 to 7) are rather variable. The relative 
dimensions of the terminal ‘‘finger’’ show considerable diversity. 
The number of bristles between the terminal ‘‘finger”’ and the sub- 
basal ‘‘finger”’ varies at least from 1 to 3; also, the size and out- 
line of the sub-basal ‘‘finger”’ is subject to some variation. (PI. ITI, 
figs. 13, 14.) Similarly, the character of the tarsal appendages (PI. 
ILI, figs. 8 to 12) exhibits some modifications. 
Proportion of sexes.—Worsham (1910) states that in Georgia less 
than one-fourth of the fertilized eggs produced males. In a large 
number of rearing tests conducted at Batesburg the total male and 
female progeny from fertilized eggs was found to be 39.7 per cent 
and 60.3 per cent, respectively. The ratio of four males to six females 
represents fairly well the usual proportion of the sexes. When de- 
velopment is normal, the ratio of females to males (based on the 
foregoing computation of sex ratio) will remain about six to four. 
At the time of the active migratory movements of females, with their 
resulting isolation without male individuals, reproduction takes place 
parthenogenetically for awhile. Since cereiae | eggs invariably 
bring forth male individuals, the progeny of these isolated unfertilized 
migrants will be males, and following such migrations a superabund- 
ance of males is frequently observed; also, the ability of males to 
evade capture by predatory enemies or to withstand the action of 
wind and rain may account partly for the increased number of males 
which occurs at times. In the fall there is a tendency for the males 
to predominate which insures the fertilization of the females during 
the winter. 
Copulation.—Several writers have described the act of copulation 
of the red spider. Perkins (1897) states that the sexes pair at once 
after the last molt and that one female may receive several males if 
