BULLETIN 190. 



MACROSIPHUM DESTRUCTOR AND MACROSIPHUM 

 SOLANIFOLIL* 



Edith M. Patch. 



Because of their similarity and the consequent lack of satis- 

 factory specific characters in descriptions, many of the aphides 

 belonging to the genus Macrosiphum have become confused 

 both as to their status in literature and in collections. Some 

 12 years ago I questioned one of our most careful aphidists 

 concerning M. pisi and he replied with a laugh, "Pisi ! Well, 

 that's a composite species all right. All big green Macrosi- 

 pha not otherwise easily placed are pisi." 



A few years ago a second aphidist who has spent many years 

 working over these insects told me with a half whimsical shrug 

 of despair, ''If an aphid is a Macrosiphum, then I do not know 

 the species." 



It was with this confusion in mind that a critical examination 

 of solanifolii was undertaken for characters which would sepa- 

 rate it from closely allied species. I found that this aphid has 

 been listed as "pisi" in certain aphid collections and presume 

 that it may be mixed with "pisi" in literature. What pisi 

 Kaltenbach is I do not know. There seems to be no reason 

 to be sure that pisi has not been a composite species in Europe 

 as well as in America "both in collections and in literature. It 

 is on account of this uncertainty that in this paper the whole 

 pisi proposition is relegated to Europe where it should first be 

 straightened out and "the destructive green pea-louse" of 



*Papers from the Maine Agricultural Experiment Station : Ento- 

 mology No. 47. 



