114 II. Abschnitt. 



doors in breeding cages at La Fayette, Ind. and at Charlottesville, 

 Va., and have been found on the small grains throughout the 

 fall, in the winter, and again in the early spring, so they doubtless pass 

 the winter both in the egg and as viviparous females in the Northern States. 

 It is doubtful whether eggs and stem mothers normally occur much south 

 of latitude 35° unless it is in higher altitudes" (Phillips 1916, p. 470). 

 Vielleicht findet auch bei uns eine Überwinterung auf Wintergetreide 

 statt (vgl. van der Goot 1915, S. 69). 



Macrosiphum' pisi Kalt, verhält sich genau so wie Macrosiphum 

 granarium. ,,In the latitude of La Fayette, Ind., the species winters both 

 as living viviparous female, usually wingless, and as egg. Farther north 

 it may winter exclusively in the egg stage, although our observations are 

 not complete on this point, while farther south, in the latitude of Tennessee, 

 the sexual forms, which lay the overwintering eggs, are rare, the insect 

 ordinarily passing the winter as living plant-lice, both wingless and winged 

 forms being able to withstand the lower temperatures in that latitude. 

 Still farther south we know only the viviparous females and our obser- 

 vations lead us to believe that the species may reproduce viviparously 

 indefinitely in localities where the winters are quite mild" (Davis 1915, 

 p. 26). Auch von Virginien berichtet Smith (1915), daß Macrosiphum pisi 

 mit viviparen Weibchen überwintert. 



Macrosiphum rosae Reaum. schließt sich in ihrem Verhalten den 

 beiden anderen Macrosiphum- Arten an. „In a climate as mild as 

 that of southern California this insect reproduces continuously throughout 

 the year and undoubtedly is capable of reproducing asexually and vivi- 

 parously for an extended period. While under Observation it has 

 been found giving birth to living young throughout the entire year, 

 and the writer has been unable to find eggs during the same period. 

 It may be that in a climate such as exists in that part of the country» 

 where very cold weather does not occur and where the roses continue to 

 grow all winter, sexual forms and eggs of this species are not produced, 

 at least until parthenogenetic reproduction causes deterioration. In other 

 parts of this country where the winter conditions are more severe the rose 

 aphis passes the winter in the egg stage" (Russell 1914, p. 5). Experi- 

 mentell ist von der Rosenblattlaus schon von Kyber (1815, S. 12) be- 

 wiesen worden, daß sie sich im Zimmer auf Rosen dauernd parthenoge- 

 netisch vermehren läßt. Kyber setzte den Versuch durch vier Jahre 

 hindurch fort (vgl. auch Morgan 1909, S. 371) und angesichts des Ver- 

 haltens der Art und ihrer Verwandten in Gegenden mit Treibhausklima 

 ist es nicht nötig, die Exaktheit seiner Versuchsanstellung zu bezweifeln, 

 wie das z. B. Schleip (1912, S. 222) tut. Auch Klodnitzki (1912, S. 475) 

 erkennt Kybers Versuche wenigstens für die hellgrüne Varietät von Macro- 

 siphum rosae an, meint aber, daß bei dieser „wahrscheinlich die geschlecht- 

 lichen Tiere nur im Laufe großer Zeitperioden und in kleiner Zahl vor- 



