582 
DIPTERA. 
seed through the middle of the stem, and, having reached a 
proper height, escapes from the hollow of the straw to the 
outside, where it takes the pupa or flax-seed state. The 
fact that the Hessian fly does ordinarily lay her eggs on the 
young leaves of wheat, barley, and rye, both in the spring 
and in the autumn, is too well authenticated to admit of any 
doubt. If, therefore, the observations of Miss Morris are 
found to be equally correct, they will serve to show, still 
more than the foregoing history, how variable and extraordi¬ 
nary is the economy of this insect, and how great are the 
resources wherewith it is provided for the continuation of its 
kind. 
The foregoing remarks were written in 1841. Since that 
time, the communication, to which they refer, has been 
printed,* and this has been followed by the publication of 
several other articles,* on the same subject, by Miss Morris. 
This ingenious and persevering lady has also favored me 
with letters concernins: her investio:ations, and with some 
of the flies. The latter were sent, as she says, “ to convince 
me, at least, that she had not mistaken a curculio, moth, 
or bee for a Cecidomyia.” Miss Morris has come to the 
conclusion that this insect is a different species from the 
Hessian fly, for which it had previously been mistaken, 
and has given to it the name of Cecidomyia cuhnicola. Ac¬ 
cording to her, the fly “deposits its eggs early in June on 
the grain, in or over the germ. The eggs remain unhatched 
until the grain germinates, but when the plant has grown 
about three or four inches, the worm may be seen, with 
the aid of a strong magnifying-glass, feeding above the top 
joint, in the centre of the culm, where it remains until it 
arrives at maturity. Should this occur before the culm 
has become hard, the worm eats its way through the joint, 
inside of the straw, and makes its escape at the root, as- 
* Transactions of the American Philosophical Society, Philadelphia, New 
Series, Vol. YIII. p. 48. Proceedings of the Academy of Natural Sciences, 
Philadelphia, Vol. I. p. 66; Vol. III. p. 238; and Vol. IV. p. 194. 
