26 BULLETIN 416, U. S. DEPARTMENT OF AGRICULTURE. 
Approximate date of reduction in numbers.—During each of the four 
years of the red-spider investigation there has occurred at some time 
of the season a sudden reduction in the numbers of the pest due to 
the abundance of natural enemies. Unfortunately, this is not general 
and simultaneous throughout the South. Furthermore, the mite 
reduction occurs at different times from season to season. In 1911 it 
did not take place in central South Carolina until about the 1st of 
September, whereas in 1912 the pest was controlled as early as July 10. 
In 1913, July 20 marked the approximate date of decimation, and in 
1914 the phenomenon occurred about July 20. For the four seasons, 
’ the average date of the reduction of the red spider by its insect ene- 
mies is found to be about July 15. 
Following these seasonal decimations the mites are often reduced 
almost to extinction, which naturally reacts against the predatory 
species in due time, and in their absence a secondary impetus is 
usually noted in the development of the red spider. These second- 
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Fic. 8.—Curve representing the 4-year composite seasonal status of the red spider in central South Caro- 
lina. The depression of the line in June represents the decimation arising through the activity of 
predatory enemies. (Original.) 
ary occurrences seldom result in serious infestations, but have the 
result of restoring somewhat the status of previous cases. This 
numerical revival may be looked for usually between the middle and 
last of August in South Carolina. (See fig. 8 for seasonal status curve.) 
Fall and early winter status.—In parts of the world where the red 
spider hibernates the mites prepare to leave their host plants at the 
approach of winter and seek shelter in the ground or under the bark 
scales at the base of the trunk or stem of trees. In South Carolina, 
the mature mites assume the characteristic orange-yellow color with 
the arrival of late fall. 
The mites which live through the winter are to be found usually 
on the basal leaves of a few dooryard plants, such as English violet, 
hollyhock, strawberry, and mustard, and upon several native species 
of weeds, etc., which offer green leaves. Every stage, from egg to 
adult, of both sexes has been repeatedly encountered during winter. 
The immature individuals produced in brief intervals of favorable 
