THE RED SPIDER ON COTTON. . oS 
rearing cells attached close to the ground quicker development 
resulted than in those attached higher on the plant. As this arises 
through heat reflection from the soil, the rearing cells were attached 
usually at points 3 or 4 feet from the ground in order to eliminate this 
surface radiation in so far as possible. 
SEASONAL HISTORY. 
Over-wintering habits—Several [European writers bave stated 
that the common red spider of the Continent passes the winter in a 
state of hibernation under bark scales or in the ground. Dugés 
found this species under stones 
and concluded that they reached 
the ground with the falling 
leaves. Von Hanstein (1902) 
found them during the winter in 
large. numbers in the ground 
near trees which had been se- 
verely infested. He states that 
mites are often so thick about the 
crown of the tree roots that 
when the soil is removed they 
become plainly visible from some 
Tittle distance, and adds that the 
red spiders fashion wintering 
quarters in the protective crev- 
ices of the bark. In Colorado, 
Weldon (1909) determined that 
the winter is spent in the ground, 
and states that myriads of red 
spiders were found below the soil 
surface at the crowns of trees 
Be on which they had been feed- Fic. 7.—Type of isolation cell employed for the 
ing. Some were found at a dis- life-history and other developmental studies of 
tance of 10 feet from the trees, ae spider. Attached to violet leaf. (Orig- 
where they had crawled beneath 
clods of soil to hibernate. Weldon states that hibernation begins before 
the cold weather sets in, the first downward migration of mites occur- 
ring toward the end of July. Wilson (1911) (Batesburg, 1910) enter- 
tained the belief that the red spiders overwinter on cotton plants near 
the base of the stalk, and was certain that they hibernate about the 
roots of cultivated violets. Worsham (1910) seems to have been the 
earhest investigator to recognize the fact that in the Southeast, at 
least, the red spider passes the winter actively in the adult stage, 
and even propagates sparingly at temperatures slightly above 
freezing. He found small colonies housed during the winter on 
