88 
field August 31, and these wintered over in the cages in this stage. 
Examinations of field conditions December 13 showed the species 
to be abundantly present in the larval stage only. The hibernating 
larvae in the cages pupated between the 21st and 25th of the fol- 
lowing April, and adults emerged May 2. This generation may be 
regarded as the first of the year. Eggs from these adults, begin- 
ning the second generation, were seen May 2-4, and began to hatch 
May 13. Pupation occurred June 3-1 1, and adults appeared June 
II ( ?) and 19. In another lot of larvae of this brood, pupation oc- 
curred June 17-22, and the adult stage was reached June 23- 
July I. No eggs of the third generation were secured fron": 
these adults, but additional pupae of the second generation from 
the field June 16 gave adults June 18-26, from which eggs of the 
third generation were obtained beginning June 23. These began to 
hatch June 29. The larvae pupated July 19-23 and these pup^e 
became adults July 25-31. Eggs of the fourth generation from 
these adults were first noted July 28, and these hatched August 2 
and 3. Thirteen larvae pupated August 18-22, and gave adults Au- 
gust 24-29. This fourth generation may properly be correlated 
with the larvae of August i, the pupae of August 3-17, and the 
adults of August 12 and later, of the preceding season. From the 
adults of August 24-29 eggs were obtained August 31, from which 
larvae began to hatch September 4. which entered the winter with- 
out transformation, belonging therefore to th.e first generation of 
the following season. 
The s]iecies produces consequently four generations in central 
Illinois, not two or three as has been previously supposed. Table 
II shows gra]:)hically the distribution of generations and stages 
tlirnout the season. 
TABLE II 
Larva 
APRIL 1 MAY 1 JUNE 
JULY 
AUGUST 
SEPTEMBER 
OCTOBER 
i . - - 
11 
n 
_.n. 
m 
lU 
ni 
I. 
TV 
IV 
i- 
-L 
n 
n 
IV 
The egg period in the second generation, in early May was 9 
or 10 days; during the remainder of the season it was 5 or 6 days. 
The larval period, except that of the hibernating generation, varied 
from 29 days in May to 16 in July. The pupal period of the third 
and fourth generations varied from 6 to 10 days; the maximum 
for the second generation was at least 10 days and probably more. 
The eggs are oval and flattened, varying in size from .4X5 nim. 
to .6X-7 nim. They are placed singly, very closely attached and 
.1 
