1927 ] The Ichneumon Fly , Epiurus pterophori Ashmead 227 
OBSERVATIONS ON THE .ICHNEUMON-FLY EPIURUS 
PTEROPHORI ASHMEAD. 
By Magel C. Wilder. 
Cornell University, Ithaca, N. Y. 
The stalks of the evening primrose ( Oenothera lamarckiana ) 
are very commonly found infested with larvae of the moth, 
Lophoptilus eloisella. These larvae are borers in the pith cavity 
of the stalks. They hibernate in the stalks. In autumn each 
larva prepares itself a hibernation chamber in the stalk by setting 
off a section of the empty pith cavity by building two partitions 
of frass and silk a little further apart than the length of its own 
body, and by lining the chamber so formed with a thin trans- 
parent film of silk. On splitting apart the pith cavities in 
autumn a number of such chambers may often be found in a 
single stem. But in some of these chambers, instead of the 
yellow moth larva there is found the whitish larva of a rather 
large hymenopterous parasite. The rearing of this parasite was 
undertaken at the suggestion of Professor James G. Needham 
and continued under his kindly direction. It proved to be the 
larva of the ichneumon fly, Epiurus pterophori. 
The evening primrose grows wild in vacant lots, and was 
gathered in a number of places at Ithaca, N. Y. The stalks were 
first brought into the laboratory and examined on March 13th. 
The moth larvse were found distributed throughout the stalks, 
occurring very frequently. The larvse of Epiurus pterophori were 
found to occur, seldom more than one in a stalk in a very small 
percentage of the stalks examined. Primrose stalks collected 
from certain places contained none. It is always found within a 
hibernation chamber but in no particular region of the stalk, and 
the head capsule together with other skin fragments of Lophop- 
tilus have been found with it. This indicates the parasitic nature 
of Epiurus pterophori. 
The larva is yellowish- white, flattened dorso-ventrally, and 
reposes normally in its cell in a curved position. The larvse 
measure from six to seven millimeters in length and are about 
one millimeter in breadth. Four narrow chitinized plates are 
