204 MAINE AGRICULTURAL EXPERIMENT STATION. IQIS- 



these two species should they ever be found to occur upon the roots ui 

 the same trees. 



Schisoneura americana is a name which until recently has been com- 

 monly applied to two distinct species by American entomologists. 



One of these species inhabits the leaf cluster or aphid rosette of the 

 American Elm.* This migrates to apple, several varieties of mountain 

 ash (Pyrus sp.) and to hawthorn (Crataeus), where it was familiar 

 as lanigera. long before its identity with the aphid of the elm rosette 

 v/as suspected. The life cycle of this species so far as personally 

 ascertained by the writer is recorded in Bulletin No. 217 of this Station. 

 The admirable publication by Mr. A. C. Baker should be consulted by 

 everyone studying this insect. (1915. The Woolly Apple Aphis. Reporc 

 No. loi, U. S. Dept. Agric. Office of the Secretary). 

 ■ The other species to which the name Schisoneura americana has been 

 commonly applied is the aphid discussed in this present paper. Siin-c 

 the name lanigera takes care of the rosette species on elm as well as on 

 apple, S. americana seems to be left free for the aphid curling or foiling 

 the leaf of the American Elm. Riley's description of the leaf deforma- 

 tions caused by S. aniericanai seem to indicate clearly enough that he 

 originally applied this name to 'both these species as his successors have 

 certainly done until recently ; and the synonomy "schisoneura lanigera 

 (americana in part, of authors)," correctly designates the "rosette 

 aphid" of the elm. 



The writer has observed and previously recorded migrants frorh leaf 

 curl upon mountain ash (Pyrus sp.) in company with those from the 

 rosette. The mountain ash concerned with that record was very near 

 elms and whether the presence of leaf curl migrants upon that tree 

 was accidental or whether their progeny will accept its roots as they do 

 those of the Juneberry still remains to be ascertained. 



The writer's first announcement of the migration of lanigera from elm 

 to apple (Science Vol. 36, pp. 30-31) was a record of migrants from elm 

 leaf curl establishing a successful colony upon apple seedlings. From 

 the fact that subsequent successful migrations to apple have been from 

 rosettes and not curls, there seems to be a possibility that rosette mi- 

 grants may have been present accidentally in the curls which were 

 collected in the South and sent to Maine, and that they were really 

 the progenitors of the successful colony. Where curls and rosettes are 

 present on the same tree such a mixture of the winged forms sometimes 

 happens. Whether some southern elms support normally an elm curl 

 form of lanigera or whether that initial record will stand as unique and 

 without subsequent verification as to the type of the deformation con- 

 cerned, remains to be seen. 



*Fies, 70 and 71, Bulletin 217. Maine Agric. Exp. Sta. 



•t "Curling and gnarling the leaves of the White Elm {Ulmus americana), forming 

 thereby a sort of pseudo-gall. The curl made by a single stem-mother in the spring 

 takes the pretty constant form of a rather wrinkled roll of one side of the young leaf, 

 but, according as there is more than one stem-mother, or as several contiguous leaves 

 are affected, the deformation assumes various distorted shapes, sometimes involving 

 quite large masses of the leaves." 



