s 
BULLETIN 1035, U. S. DEPARTMENT OF AGRICULTURE. 
occurring during the red spicier season also interfere with the regu- 
larity of the generations. Activity of the red spider usually com- 
mences during the latter part of August and ceases the first part of 
April, giving an active season of about 240 days. The average dura- 
tion of the life cycle is 1l2 days, which would give 17 generations. 
This would be true where no interruptions due to climatic conditions 
occurred, and when no other factors interfered with the normal activi- 
ties of the mites in the field. 
Shedding of the foliage. — During the winter months the foliage 
may be termed " dormant." no new growth being present on the trees. 
Usually during the latter part of March and April the avocado com- 
mences to bloom and the older leaves, which have served their purpose 
to the trees, commence to fall. With the shed leaves many mite- are 
lost and do not regain positions on the trees. During the latter part 
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p 1G 4. — Curves showing 2-year composite seasonal status of the avocado red spider in 
southern Florida. The decimations arising through the amount of precipitation are 
The most important controlling factor in the activities of the species. 
of April very little old foliage is present and a remarkable reduction 
of red spiders is apparent. A few old leaves, however, always re- 
main on the trees until the newer growth has hardened and thus 
enable the red spiders to remain continuously on the trees and to in- 
fest the newer growth when it hardens. 
Climatic control. — Climatic conditions existing in Florida influence 
the development and activity of the red spider to a marked degree. 
This particular species, as has already been stated, confines its depre- 
dations to the upper surface of the foliage. The species so working 
is exposed to the weather conditions. Hence during the period of 
the life cycle or seasonal cycle there is a series of fluctuations in 
number-. In April, as the rainy season approaches, the red spider 
barely maintains existence. (Fig. \.) During the months of June. 
July, and August no pronounced gain is made, but toward the latter 
part of October the avocado ceases to produce new growth, the red 
spiders commence to make their appearance in greater numbers, and 
increase during November and December. They usually reach the 
maximum number during January and February, and decrease 1 
again toward March. Precipitation is the one climatic factor im- 
portant in reducing the red spiders during the spring and summer. 
