274 [Senate 
completed their transformations ; a corresponding number of dead 
wheat-flies being found attached to a straw in the upper part of the 
vial. Prof. Henslow thinks that it is only those larvae that are 
punctured by ichneumons, that leave the wheat-ears and enter the 
ground; but the facts now stated show that this opinion is erro¬ 
neous. 
On removing the earth from the vial above alluded to, the cases of 
the pupa from which the flies had proceeded, were found very per¬ 
fect. These conclusively showed that vhe real pupa is not formed 
until in the spring, and that it is then altogether different in form 
from what has been described by writers as its pupa. It corresponds 
identically in its appearance (perhaps with the exception of color) 
with that of the Cecidomyia Salicis , as exhibited in the first volume 
of the American Quarterly Journal of Agriculture and Science. 
Plate 2, fig. 1. It also closely resembles the figure of the pupa of 
Cecidomyia Pini ?. as given from De Geer in Westwood’s Introduc¬ 
tion to the Modern Classification of Insects, vol. ii. p. 518, fig. 125,. 
No. 7.* Its length is slightly less than that of the dormant larva. 
The antennse, legs and wings, are each enclosed in separate sheaths, 
which lie externally to the integument in which the body is envelop¬ 
ed. The three pairs of legs all lie parallel and in contact with each 
other upon the breast, reaching far down past the tips of the wings ; 
the inner pair being shortest, and the outer pair longest. Judging 
from the analogy afforded by the Cecidomyia Salicis, I presume the 
wheat-fly only remains in its pupa state three or four weeks in the 
latter part of May and the fore part of June. 
ITS NATURAL ENEMIES. 
One of the most effective natural destroyers of the wheat-fly, is 
undoubtedly our common yellow-bird (Fringilla tristis, Lin.) Fields 
much infested by the insect, have been for many years recognized 
even by passers on the highway contiguous to them, by the rough 
and ragged aspect of the heads of the grain (Plate, fig. c). I am 
not aware that the cause of this peculiar appearance has ever been sta¬ 
ted in any of the communications that have appeared in our agricultu- 
• I cannot but regard the figure here referred to as inaccurate, in representing tho 
wings as enclosed in one common case, over which the legs are laid. The tips of the 
wings should probably be rounded, instead of being brought to a point. 
