itiU 
DESCRIPTION AND SEASONAL HISTORY. 19 
portions. Under the microscope the surface of the egg is very 
shghtly roughened and sculptured. 
Mr. Ainshe, who made a careful study of the egg (fig. 3) at oviposi- 
tion and later, found that at time of laying the egg was a mere sac, 
the shell being little more than a transparent, homogeneous envelope 
or membrane. As segmentation proceeded this membrane became 
very faintly pitted, and under the microscope with proper illumina- 
tion barely discernible reticulations, both pentagonal and hexagonal, 
were apparent. Both ends and sides seemed equally reticulated, the 
areolation being perhaps a little smaller at the ends. After the larva 
emerges the shell that remains is a transparent structureless mem- 
brane with no trace of reticulation. 
The number of eggs placed in a cavity varies greatly, there some- 
times being not niore than 2 or 3, ranging up to over 30; probably 10 
would be about the average number, although these figures are of 
course only approximate. Mr. Parks found that during the &st half 
of April the number ranged from 3 to 18, averaging 7 or 8; during 
the last half and early May the number increased, 25 or 30 being the 
maximum, with an average of 8 or 9. With reference to the number 
of eggs that may be deposited in a single alfalfa plant, the one shown 
beside the hat in Plate I, figure 1, examined on April 23 — at which 
date oviposition was still in progress and the beetles preparing for 
oviposition were still exceedingly numerous in the fields — indicated 
that this plant at this date contained nearly if not quite 1,300 eggs. 
Of course, in fields where the alfalfa grew up thickly there would be 
a relatively less num^ber per plant, but these figures serve to illustrate 
the origin of the countless myriads of larvae that swarm over the 
plants in an alfalfa field and render more easy of comprehension the 
destruction shown in Plate III, figure 1. The difference between 
uninjured and affected plants is shown in Plate III, figure 2, a and h. 
Other ravaged fields are shown in Plate TV, figures 1 and 2, in con- 
trast with figure 3 of same plate. 
In the Salt Lake VaUey oviposition has been found to take place 
earlier on the bench lands than lower down in the vaUey itself. 
Egg-Laying Period. 
The period of egg laying is a matter of considerable significance, 
since in some degree it will decide the question of efficiency or prac- 
tical measures of control. As is usual with insects, after a female 
has exhausted her supply of eggs she dies and there is no second 
depositing of eggs by her during that season. The actual time 
required for the individual female to deposit her supply of eggs is of 
course influenced by the weather. In 1909 egg laying began in the 
fields early in April, and eggs were found in greatest abundance during 
the last of May and the first of June. In 1910 egg laying began early 
