16 
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larvae, however, was higher in the 
progeny of virgin females, and few 
survived to become adults. It may 
be that larvae wanting male parents 
are lacking in vitality and when 
developing to the adult produce an 
insect with less viability. This is 
indicated by the death of a great 
percentage of the larvae under ap- 
parently favorable conditions and 
the shorter life of adults from eggs 
laid by unfertilized females. 
IPARASITES. 
Only two species of natural ene- 
mies were obtained from the experi- 
ments performed at the eastern field 
station, East Falls Church, Va. These 
were Dibrachys nigrocyaneus Norton 
and a species of Eurytoma. Britton 
and Zappe 8 record the following: 
Hymenoptera: Dibrachys nigrocyan- 
eus Norton, Monodontomerus dentines 
Boheman, Dibrachoides verditer Nor- 
ton, Delomerista n. s-p.,Cerambycobiu$ 
sp. (probably new), Eurytoma sp., 
Hemiteles utilis Norton. Diptera: 
Exorista petiolata Coquillett. 
All parasites specifically identified 
are native species, with the excep- 
tion of Monodontomerus dentipes Boh., 
which is a European species already 
recorded from the United States. 
Dibrachys nigrocyaneus was rather 
abundant, much more so than any of 
the other species, and Britton and 
Zappe state that only the first three 
species recorded in their list given 
above were reared in sufficient num- 
bers to indicate that they are at all 
effective in holding the pest in check. 
Table 9, from Britton and Zappe, 
gives the general results of an exam- 
ination of cocoons collected during 
the winter of 1916-17. 
A short experiment on the length 
of life of Dibrachys nigrocyaneus Nor- 
ton was performed. From 65 adults 
caged without food all the males died 
within three days and all females 
» Britton, W. E., and Zappe, M. P. The imported pine sawfly. In Conn. Agr. Exp. Sta. Bui. 203, p. 
273-290,1917. See p. 283. 
