Bulletin No. 220 



WOOLLY APHIDS O'F THE ELM.* 

 Edith M. Patch. 



Since the publication of Bulletin 203 about one year ago, the 

 elm aphids belonging to the genus Schizoneura have been mak- 

 ing such rapid history that that publication is not only out of 

 print but also out of date. It is the purpose of Bulletin 217 

 and the present paper to bring together what information I 

 have on this group of elm aphids, more as a report of progress 

 in order to clear away certain previous confusions than as an 

 attempt at a complete treatment. 



I have received very considerable aid in this study from 

 entomologists in widely separated parts of this and- other coun- 

 tries and express my appreciation of such help in general rather 

 than in specific terms, not from any desire to assume credit for 

 data worked in accordance with suggestions from others but in 

 order that no one else need find himself made responsible for 

 the manner in which these fragments are presented. 



While it is to be regretted that we have not the total stories 

 of all the species discussed it seems wise to bring the account 

 up to date, trusting that the missing links will be forthcoming 

 sometime, somewhere. 



The present discussion takes no account of such species as 

 have as yet been collected only in the far West as those can 

 most fittingly be introduced by the entomologists who have been 

 observing them at close range. 



Among the points of specific value in separating these aphids 

 are the antenna of the stem females with especial reference to 



* Papers from the Maine Agricultural Experiment Station : Ento- 

 mology No. 68. 



