66 
LIFE HISTORY. 
The pupal period varies greatly, according to the season. Thus, in 
hot weather in July a number of loopers were observed by the writer 
to transform to pupae July 5 and to issue as moths on the 11th, or in 
six days, the temperature indoors averaging about 85^. Another lot 
of pupae taken from celery in the field October 7 did not develop moths 
until the 29th, or in twenty-two days. The weather was cool, but the 
temperature was not noted, so it is plain that we have a pupal period, 
varying according to temperature, of from one to three weeks. No 
definite records can be found of the duration of the egg or larval periods, 
but assuming three generations for the Upper Austral zone, where 
this species seems to attract more attention than in the South, we 
can safely assume from analogy with the observed pupal periods 
and other knowledge of related species that the egg period will vary 
from four to ten or more days, according to temperature; that the 
larva may undergo all its changes (five stages in number) in from 
two to four weeks, the minimum of two weeks being estimated from 
the fact that the larvae grow so rapidly, and the maximum, four weeks, 
from our knowledge that the insect breeds later in the season than 
nearly any other injurious species of its kind. 
In reviewing the life history of this species, Dr. Lintner (1. c.) 
stated that there were only two generations produced during the year, 
and this is perhaps true of its extreme northern limit. ' Mr. Sirrine, 
however, states that it is apparentl} T three-brooded on Long Island, 
and that hibernation probably occurs both as adult and pupa. 
If the last generalization is correct it would seem probable that four 
generations may possibly be produced in the District of Columbia, but 
the writer is inclined to believe that there are only three, and that 
hibernation takes place chiefly in the pupal stage. A fourth genera- 
tion is evidently attempted, but fails to survive the winter. 
The time when the moth makes its first appearance in the District 
of Columbia or elsewhere appears not to be recorded. Few individuals 
survive the winter northward, but the propagation of the species is so 
rapid that by the time autumn is reached great numbers of larvae are 
produced which do much damage to crops in cultivation at this time. 
NATURAL ENEMIES. 
PARASITES. 
This cabbage looper is unusually susceptible to bacterial and fun- 
gus diseases; it is also preyed upon by birds and other insectivorous 
animals and by parasitic and predaceous insects. Its most efficient 
insect destroyer in the field in Maryland, Virginia, and the District 
of Columbia is a minute chalcis fly {Copidosorna t? v uncatellum Dalm.), 
an imported European parasite, which has evidently selected this 
