ON THE NORTH AMERICAN CECIDOMYIDAE. 



BY BARON R. OSTEN-SACKEN. 



It is a peculiarity of the family of Cecidomyidce that its natural 

 history has always been studied in close connection with its classi- 

 fication. This is owing chiefly to the fact that the gall, the produce 

 of the insect in its first stage of life, is generally a more striking 

 object in nature than the insect itself. The latter small, tiny, dif- 

 ficult to preserve on account of their extreme delicacy, still more 

 difficult to distinguish from their congeners on account of the uni- 

 formity of their appearance and coloring, would afford a very un- 

 satisfactory object of study, unless in connection with the varied 

 deformations which their larva? produce on plants. The study of 

 this family, different in this respect from most of the other families 

 of insects, cannot be prosecuted apart from the observation of living 

 nature, and for this very reason will always be a monopoly of the 

 naturalist so situated as to afford such observations. 



The aim of the present paper is to direct the attention of 

 American entomologists to this most interesting subject, by giving 

 an account of the observations already made on the North Ameri- 

 can Cecidomyidce, as well as a general introduction to the study of 

 the habits and the classification of this family. The latter has been 

 extracted chiefly from the two following admirable monographs: — 



Loew, Dr. H. Dipterologische Beitrage, Part fourth, Posen, 1850, with a 

 plate. (Contains a monograph of the European Cecidoiuyidx.) 



Winnertz, J. Beitrag zn einer Monographie der Gallrnhcken. In the Lin- 

 nsea entomologica, Vol. VIII, Berlin, 1853,jvith four plates. 



I. On the classification of the CECIDOMYID^!. 



In the sketch of a systematical distribution of the Diptera, given 

 by Prof. IT. Loew in this volume, he has mentioned the difficulties 

 attending a sharp definition of this family, and has shown that it 

 may be naturally divided in two sections. 



The species embraced in the first section, which he calls Cecido- 

 myina, h#ve four longitudinal veins on the wings, the last two of 



