57 
in that vicinity. We received, August 6, specimens of this species 
from Dr. E. K. Harding, Carterton, Va., where the} 7 were attacking 
cabbage. 
NUMBER AND OCCURRENCE OF GENERATIONS. 
Observations conducted during the season of 1900 indicate the pres- 
ence of four generations in the District of Columbia and vicinity. 
From larva? obtained in the latter days of May and in early June in 
different fields of cabbage, in and near the District of Columbia, moths 
were obtained during the last days of June and until July 6. 
The second generation produced from the first of these moths and 
placed in a rearing cage July 2, issued August 1, having passed all 
stages in just thirty days, which will come very near to being the mini- 
mum period for this latitude, since the heat was excessive during the 
greater part of the month of Jury. 
The third generation began to appear in the rearing cages, on Sep- 
tember 1, from moths which issued August 1, or in thirty-one days, 
the temperature during that period, with the exception of a few days, 
having been about the same as in Jul} 7 . 
The fourth generation, as might naturally be expected, failed to 
develop in confinement, and it seems probable that this was the last 
generation produced in the field. This was only apparent, however, 
for after repeated failures to find the larva in the field, a colon} 7 was 
taken September 21 in a small head of cabbage. This last colony was 
obtained on the Department grounds, and was evidently the progeny 
of moths which had purposely been liberated from our rearing jars, so 
that it represents in all probability the normal fourth generation. 
It must not be supposed from the above that there is any such 
regularity of development except in a single season and in a given 
locality. At other times, from specimens gathered where the tem- 
perature was somewhat different, moths were reared July 14; larvae 
were obtained, nearly all mature, July 30. From other lots moths 
have issued August 9 and 10. In one instance larva? were noticed to 
mature August 20, and to develop as moths September 1, giving ten 
days for the period occupied by the larva in the cocoon. Perhaps 
two or three days elapsed before the larva? changed to chrysalides. 
In still another case larva? were found to enter the earth August 29 
and 30, and moths developed September 9, giving about the same 
period as just mentioned. 
SUMMARY OF LIFE HISTORY. 
Observations conducted by the writer go to show that in many 
respects this cabbage worm, although the larva of a moth, conforms 
very closely in its life economy to the imported cabbage butterfly. 
It is attacked by some of the same natural enemies, and appears to 
differ from the imported species only in unimportant details. Like 
