CONTROL OF CITRUS THRIPS IN CALIFORNIA AND ARIZONA. 5 
die off as the weather grows colder, until by the middle of January all 
have disappeared. The winter is passed only in the egg stage. Eggs 
deposited in the leaves and stems, mostly during late August, Septem- 
ber, and October, hatch and the larve appear in March, April, and 
May. 
The average duration of the egg stage of summer generations varies 
from 10 to 18.8 days during Mo and June, 6.8 to 8.5 days in July and 
August, and 17 to 18.8 days in September and October. 
The average larval stage varies from 6.6 to 13.7 days during April 
and May, 4.2 to 9 days from June to August, and 6.7 to 11.2 days in 
September and October. 
The average pupal stage varies from 4.7 to 13 days during April and 
May, 2.8 to 5.1 days from June to August, and 5 to 19.9 days from 
September to November. 
Pupation takes place in crevices on the tree trunk, in dead leaves 
and rubbish under the trees, and under clods and particles of trash 
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Fic. 3.—Graphic illustration of the seasonal activities of the citrus thrips as related to blossoming and 
later growth periods of the orange, and indicating also the spray periods. (Original.) - 
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on the ground, but never in the ground. The pupa is naked, does not 
construct a cell, and is at all times capable of locomotion. 
The average duration of adult life is from 25 to 35 days, with 
extreme instances running to from 46 to 49 days. Adults can live 
from 2 to 6 days only without food. 
The number of generations in a season will depend upon the char- 
acter of the season. An early, warm spring followed by a prolonged, 
hot summer may result in the production of eight or more genera- 
tions. In seasons such as 1911, six full generations may be expected 
between the middle of April and the first of November. For pur- 
poses of control the citrus thrips must be treated as an insect having 
only a single generation a season, and with an egg-laying pera 
extending from April to November. 
