652 
Journal of Agricultural Research 
Vol. XXX, No. 7 
tering gipsy-moth eggs. It follows 
that adults of the first spring genera¬ 
tion begin issuing from gipsy-moth 
eggs about the last week of May and 
continue well into June, the greater 
number issuing during the first half of 
June. Both sexes are present in this 
and future generations, indicating that 
some, if not all, of the females which 
hibernated successfully were fertilized 
during the preceding fall. Many of 
the adults of the first spring generation 
oviposit in nonhatched gipsy-moth eggs. 
Adults of the second spring generation 
are found issuing from the beginning to 
the middle of July. Experiments have 
shown that adult Schedius often live 
five to six weeks, ample time being thus 
afforded for many adults of the first 
generation to oviposit in the new 
gipsy-moth eggs which are laid in July. 
Adult Schedius are often seen ovi¬ 
positing in gipsy-moth eggs before the 
entire cluster is deposited by the moth. 
The first fall generation issues about 21 
days after oviposition, or during the 
first week in August. A part of the first 
fall generation often has issued before 
all of the gipsy-moth eggs have been 
deposited. The generations during the 
fall so overlap one another that they 
can not be definitely separated, but 
there is time during the average* season 
from the middle of July until early in 
November for four complete genera¬ 
tions and a partial fifth. During the 
warm weather from the middle of July 
to the middle of September there is a 
generation about every 21 days. The 
last two generations require somewhat 
more time in which to develop and 
many of the Schedius within the host 
eggs which would otherwise become 
adults of the fifth generation are killed 
in various stages of development by 
severe temperatures. 
The approximate time of the appear¬ 
ance of each generation of Schedius is 
here given. The dates vary consider¬ 
ably during different seasons. 
April 10 to May 15: Hibernated fe¬ 
male Schedius active in the field. 
May 25 to June 8: Adults of the first 
spring generation, both sexes, issuing 
from host eggs. 
June 30 to July 15: Adults of the sec¬ 
ond spring generation (partial) issuing 
from nonhatch gipsy-moth eggs. 
Week of August 5: Adults of the first 
fall generation issuing. 
Week of August 26: Adults of the 
second fall generation issuing. 
Week of September 16: Adults of the 
third fall generation issuing. 
Week of October 14: Adults of the 
fourth fall generation issuing. 
November 11 and later: Adults of the 
fifth fall generation (partial) issuing. 
Cold weather causes the death of many 
of this generation within the host egg. 
REPRODUCTION ON GIPSY-MOTH EGGS 
Schedius reproduces on freshly de¬ 
posited eggs of the gipsy moth as well as 
on those in which the embryo is fully 
developed. Freshly deposited eggs 
have been kept for a month in cold stor¬ 
age at a temperature of about 30° F. 
and then exposed to Schedius. An ex¬ 
amination of these eggs showed no 
development of the embryo, and Sche¬ 
dius reproduced readily on such eggs. 
During the major part of the breeding 
period of the Schedius the host eggs are 
well developed, and at such time Sche¬ 
dius acts as a parasite of the unhatched 
gipsy-moth larva within the host egg. 
Many records have been made of the 
breeding of Schedius on dead gipsy- 
moth eggs. Some of the early work on 
breeding at the laboratory was greatly 
facilitated by using gipsy-moth eggs 
which had purposely been killed by 
being placed in hot water. In this 
manner the breeding was continued 
during the winter and spring months 
without interference from the hatching 
of gipsy-moth larvae. Gipsy-moth eggs 
have been held in cold storage for two 
years until all or practically all of them 
were dead, and then have been used 
successfully for reproducing Schedius. 
Some of the adult Schedius from the 
first spring generation oviposit success¬ 
fully in gipsy-moth eggs which have 
failed to hatch earlier in the spring. 
Schedius bred from dead gipsy-moth 
eggs are not so strong and robust as 
when bred on healthy gipsy-moth eggs. 
REPRODUCTION ON EGGS OTHER THAN 
THOSE OF THE GIPSY MOTH 
Schedius has been bred successfully 
at the laboratory in eggs of the follow¬ 
ing: Hemerocampa leucostigma S. & A., 
H. definita Pack., Callosamia promethea 
Dru., Malacosoma americana Fab. r 
Hemileuca maia Dru., H. oliviae Ckll., 
Euproctis chrysorrhoea L., and Stilp- 
notia salicis L. It is interesting to note 
that in a few cases of parasitism of a 
large egg like that of H. oliviae, several 
Schedius developed in an individual 
egg. On two occasions five, and on a 
number of occasions two and three, 
Schedius issued from a single egg. 
Parasitism of these species by Schedius 
in the field is probably of rare occur¬ 
rence, and in no case have Schedius 
been reared from any of the eggs above 
