DIPTERA. 465 



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 extra- 

 ordinary 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 concern- 

 ing her investigations, 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 dif- 

 ferent species from the Hessian fly, for which it had previously 

 been mistaken, and has given to it the name of Cecidomyia cul- 

 micola. According 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 ar- 

 rives 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, ascends the 

 straw on the outside, where it attaches itself firmly, and awaits 

 its change; the outer skin becomes the puparium. In the 

 pupa or flax-seed state, it closely resembles the C, destructor. 

 Should the culm of the wheat become prematurely hard before 

 the worm has finished feeding, as is often the case, the insect 

 will remain imprisoned for life, passing through its changes 

 inside the straw, and there perish without the power to escape, 

 unless some accidental passage be made for it. I have lib- 



* " Transactions of the American Philosophical Society," Philadelphia. New 

 Series. Vol. VIII., p. 48. — " Proceedings of the Academy of Natural Sciences," 

 Philadelphia. Vol. I., p. 66 ; Vol. HI., p. 238 ; and Vol. IV., p. 194. 



59 



