THE BLACK FLY OF CITRUS. 
29 
EGGS. 
The eggs (PI. VIII, A, B) are normally laid in spiral form, when the 
adults are undisturbed, but there is a great irregularity in the shape 
of these " masses." In fact it is doubtful if more than 50 per cent 
of the eggs are laid in this form. Egg laying has been observed as 
short a time as 18 hours after the emergence of the adults (young tree 
and petri dish experiments in the laboratory) and as long a time as 
four (or more) days in individuals of unknown previous history 
brought into the laboratory on young citrus shoots for observation. 
JO seconds pause 
first egg laid 
First egg laid 
10: 14 A.M. 
I*st egg laid 
10:2? A.M. 
y^ Iminute pause \jo seconds pause 
last egg laid 
2 minute pause 
First egg laid 
9:55 A.M. 
Last egg laid 
10:05 A.M. 
last egg laid 
female wandered away, 
1 minute pause 
first egg laid 
Fig. 
•1 minute pause 
-Diagrammatic drawings showing the procedure in oviposition of Aleurocanthus woglumi. 
In laying eggs (fig. 6) the female usually starts at what becomes the 
center of the spiral (although the inverse of this has been observed) 
and facing outward begins a series of nervous vibrations and contrac- 
tions. After from one to four such contractions and a rocking back- 
ward and forward she suddenly thrusts the end of her abdomen against 
the leaf and lays an egg, there being a noticeable contraction of the 
abdomen as the egg is expelled. During this oviposition the costal 
margins of the forewings rest against the surface of the leaf and serve 
to steady the female. The entire time for the deposition of a single 
egg including the shaking movement is usually from 15 to 30 seconds 
but sometimes takes as long as one or two minutes. After laying an 
egg the female moves forward a little, one-half the length of her body 
or more, and repeats the operation. When she has laid from 3 to 5 
