FAMILY CECIDOiAIYID.E THE GALL MIDGES 103 



stems and roots and are usually characteristic for each species. The 

 larvae may be recognized by the presence of a "breast bone" or chitin- 

 ized process lying witliin the thorax and terminating behind the head. 

 The phenomenon of pedogenesis occurs in some species belonging to the 

 genus Miastor, that is the larva? produce eggs from ovary-like organs, 

 the eggs hatch within the body and the young larvas devour the parent, 

 later escaping and completing their development externally; several 

 generations may be produced in this way, before the development of 

 adult insects occurs. 



The classification of the family is difficult and I have merely 

 emended the key given by Dr. Felt.* For the most part little can be 

 done without preparing slides of the adults, the whole insect being 

 mounted. It is advisable to preserve dried specimens as well as the 

 mounts, and the galls should always be kept along wuth the adults. 

 Study of the group should not be attempted by anyone who is not pre- 

 pared to spend years of painstaking work on his hobby. Such a study 

 would prove of inestimable value and would fully repay the student 

 for the time spent. Many of the species are serious pests, the chief 

 among these being the Hessian fly. 



I may add tliat the study of the galls themselves constitutes a 

 fascinating past-time and Dr. Felt has given us an excellent treatise 

 on this subject t and is, I believe, preparing a new and enlarged edition. 

 The series of papers published by Dr. Felt is copiously illustrated and 

 I have made free use of these illustrations. In connection with their 

 use I cannot help but call attention to the splendid cooperation of Dr. 

 C. C. Adams, of the New York State iMuseum, in furnishing the cuts 

 used for this family and of Dr. Felt for assistance and suggestions. Most 

 of the illustrations of Cccidomyida are from cuts furnished by the New 

 York State Museum. 



KEY TO GENERA 



1. Circumfila present 23 



Circumfila absent 2 



2. Wings with four longitudinal veins 3 



Wings with at most three longitudinal veins 17 



3. Fourth vein forked 4 



Fourth vein simple 10 



4. Second antennal segment greatly enlarged 5 



Second antennal segment normal 7 



* 1925. Key to Gall Midges (A resume of Studies, i-vii. Itonidida?), N. Y. State Mus. 

 Bull. No. 257. References to Parts i-vii will be found in this Bulletin. 



t 1918. Key to American Gall Insects. N. Y. State Mus. Bull. No. 200. 



