138 BULLETIN 14* 
be present. It has several generations each year, and hibernates as 
a full-fed larva in a very thin, tough cocoon. In October, 1922, a 
total of 1,061 cocoons were received from France. This shipment 
produced 500 adults, of which 56 were liberated in the field during 
1921 and the remainder were used in breeding experiments. With 
this breeding stock as a basis, a total of 28,935 adults were bred and 
liberated during 1923. In 1924, 11,341 were liberated in New Eng- 
land, 7,920 sent to Sandusky, Ohio, and 2,880 to Silver Creek, N. Y., 
for liberation. Females predominated, and through the use of a 
special emergence cage they were well mated before liberation. 
Habrobracon brevicomis Wesm. is a small hymenopteron which 
paralyzes full-grown host larvae and deposits external eggs. The re- 
sulting larvae feed externally and produce an average of 18 cocoons 
per host. From 8 to 10 generations per year would be possible with 
this parasite, as the life cycle is very short, varying greatly with 
the temperature. Hibernation occurs in the adult stage. In Septem- 
ber, 1921, a total of 1,210 cocoons were received from France. This 
shipment produced 715 males and 213 females. With this breeding 
stock as a basis, 400 adults were bred and liberated in 1921 and 
1,054,000 in 1922. Late in 1924 approximately 25,000 were liberated 
in Sandusky, Ohio, and in Silver Creek, jNT. Y. In the 1921 libera- 
tions the females averaged only 14 per cent of the total whereas 
improved breeding methods during 1922 increased the proportion of 
females to 40 and later to 60 per cent. 
Microgaster tibialis Nees is a small hymenopteron which has been 
particularly effective as a parasite of P. nubilalis larvae inhabiting 
weeds in northern France and Belgium, and is also found in corn in 
Italy. This species parasitizes second-instar host larvae, feeding in- 
ternally and emerging from the host in the late fourth or early fifth 
instar. Hibernation occurs as a full-fed larva within a very tough 
white cocoon. A total of 100 cocoons were received from France 
in 1923, and although no liberations were made during 1923 an 
attempt was made to develop a satisfactory technic for rearing 
the species. There were 449 adults and 2,815 parasitized larvae 
liberated in 1924 in the Massachusetts area. 
Phaeogenes planifrons Wesm. is a large hymenopterous parasite 
which emerges from the pupa. It is particularly valuable as a 
summer-generation parasite in Italy, according to Doctor Thompson's 
records. There were 1,460 adults liberated in New England in 1924. 
Recoveries of Foreign Parasites 
With the exception of Habrobracon brevicornis, no systematic col- 
lections for the recovery of liberated parasites have been attempted. 
The results in attempting to recover H. brevicomis were negative 
to January 1, 1925. Encouraging results, however, were secured 
with Exeristes roborator and Microgaster tibialis. Incidental col- 
lections during the summer of 1923 showed that a maximum of 8 
per cent of the corn-borer larvae were parasitized by E. roborator 
in the vicinity of the colony sites in Massachusetts, and from 1 to 
4 per cent of the larvae were parasitized in a cornfield 3 miles from 
one of the liberation points. One incidental recovery was made at a 
distance of 5 miles from the nearest point of liberation. Several 
recoveries were made of individuals of this species which had sue- 
