72 WHITE FLIES INJURIOUS TO CITRUS IN FLORIDA. 
only by a very porous cheesecloth they show absolutely no attraction 
to each other. Mating, therefore, is not so likely to occur when the 
adults are scarce, as it seems to be the result of chance meeting upon 
the leaves rather than to such a definite attraction as exists between 
males and females of many moths. 
Upon detecting the female, the male approaches her nervously, 
stopping at intervals, especially as the distance lessens, and swinging 
his body about excitedly in a semicircle, the head being used as a pivot, 
his wings in the meanwhile opening and closing spasmodically. While 
no movement is made by the female, she is repeatedly approached 
from many directions before coition occurs. More often the male lies 
alongside the female and courts her in this position, raising and low- 
ering his wings as above described, and raising and swinging his abdo- 
men from side to side. During these antics of the male the female 
remains quiet, only occasionally flittering her wings. While males 
may be seen courting females at all times of the day, it is seldom that 
one sees a pair in coitu except late in the afternoon and evening. Be- 
cause of the uniformity of color and the ease with which adults are 
disturbed and made restless the duration of copulation can not be 
stated with certainty, but it probably lasts but a short time. Experi- 
ments to determine the duration of fertility have thus far proved 
unsuccessful. 
OVEPOSITION. 
AGE AT BEGINNING OVIPOSITION. 
Virgin females in confinement have deposited eggs within 6 hours 
after emergence. In one instance 35 virgins deposited 58 eggs between 
5 and 9^ hours after emergence during summer weather, with the 
temperature ranging from 80° to 92° F. However, even at this tem- 
perature single females occasionally did not deposit eggs for over 24 
hours. Prof. H. A. Gossard x states that egg laying begins at from 
18 to 30 hours after the emergence when the temperature ranges from 
65° to 75° F. Laboratory tests have shown that lack of fertilization 
does not prevent a female from depositing eggs, but that she will 
readily deposit infertile eggs until opportunity for mating presents 
itself. 
PORTION OF PLANT SELECTED. 
If not numerous, the females deposit almost exclusively on the under 
surface of the leaves, laying over 75 per cent of their eggs on the half 
of the leaf bordering the midrib. It is only when very abundant 
and pressed for room that they deposit eggs thickly over the entire 
lower surface and more sparingly on the upper surface, the petioles, 
and the stems of twigs. Next to the portion bordering the midrib, 
the natural depressions and the curled margins of the leaf, especially 
1 Bui. 67, Fla. Agr. Exp. Sta., p. 609, 1903. 
