59 WHITE FLIES INJURIOUS TO CITRUS IN FLORIDA. 
becoming a pupa. After the first molt (see fig. 7) the legs become 
vestigial; hence thereafter it is impossible for it to materially change 
its location upon the leaf. Larval life averages in length from 23 to 
30 days. The pupa (fig. 9) closely resembles the grown larva (fig. 8) 
and requires from 13 to 304 days for development. The adult fly 
(fig. 10) has an average life of about 10 days, although several females 
have been known to live 27 days. Females may begin depositing 
eggs as soon as 6 hours after emergence and continue ovipositing 
throughout life. The maximum egg-laying capacity is about 250 
eggs, although 150 more nearly represents the number laid under 
grove conditions. Unfertilized females deposit as many eggs as 
fertile females. 
The entire life cycle from egg to adult requires from 41 to 333 
days; the variation in the number of days required from eggs laid 
on the same leaf on the same day is very remarkable. During the 
course of the year the fly may pass through a minimum of two gen- 
erations and a maximum of six generations. ‘The generation started 
by the few adults that emerge during the winter is entirely dependent 
upon weather conditions and may or may not occur. Each genera- 
tion except those started after the middle of August is more or less 
distinctly two-brooded. 
MetTHops oF StupDy. 
As it is impossible to rear citrus white flies through their entire 
life cycle on detached leaves, a gauze-wire cage was devised by the 
senior author which has proved of great value and convenience in 
‘arrying on life-history studies under conditions as nearly normal as 
it is possible to get them. This cage (Pl. VII), which is cylindrical 
in shape and open at one end, may be made any size, but one 64 
inches lofg by 34 inches in diameter has proved most convenient. 
It can easily be made by fashioning two rings of heavy wire to which 
is soldered the wire gauze, as shown in the illustration. * To the open 
end is attached a piece of closely woven cheesecloth long enough 
to extend about 4 inches beyond the cage. After the leaf, or leaves, 
to be caged have been cleaned of all stages of the white fly by means 
of a hand lens and cloth, the cage is slipped over the foliage. The 
adult flies are then introduced, if desired, and the cloth attached to 
the cage wrapped around the stem of the shoot or petiole of the leaf, 
as the case may be, in such a manner that the flies can not escape 
nor the ants and other predaceous insects enter. To keep the entire 
weight of the cage from falling on the petiole of the leaf or its short 
stem, and to regulate the position of the leaf within the cage, a cord 
is tied around the outer end of the cage and attached by the loose 
end to a convenient branch. 
