54 WHITE FLIES INJURIOUS TO CITRUS IN FLORIDA. 
Eggs in which the embryonic development is normal do not turn dark 
in color, but those killed through attack by thrips or by other agency 
frequently become bronze colored, thus resembling the eggs of A. 
nubifera from which the waxy sculpturings have been rubbed. 
DURATION OF EGG STAGE. 
That no doubt might arise concerning the exact age of the eggs 
used in obtaining the data incorporated into Table VITI, suitable 
leaves were selected from which all eggs previously deposited were 
carefully removed by the aid of the hand lens and a cloth. Similar 
attention was given the leaf petiole and the stalk, and wads of cotton 
were tied about the latter both above and below the leaf to prevent 
crawling young from reaching the leaf along the petiole (Pl. VII, fig. 
1). These preliminary steps completed, a rearing cage containing 
adult white flies was placed over the leaf and allowed to remain the 
length of time desired, usually from 1 to 24 hours, with preference 
shown the latter number. The cage was then removed and an 
empty one put in its place. By this method all doubt was removed 
as to the period of time over which deposition took place. As there 
is scarcely a leaf in a grove infested with the citrus white fly that 
does not bear from a few to many eggs, this becomes an important 
point and failure in its recognition has led in the past to statements 
greatly underestimating the minimum duration of the egg stage dur- 
ing the warmer months. 
