BIOLOGICAL STUDIES ON THREE APHIDID^. 157 



being winged has ever been made. The eggs began to hatch in the 

 insectary March 16 (1907), and it is probable that in the field the 

 hatching period is chiefly the month of April. 



Sorghum and broom corn are the usual plants infested by this 

 species, and upon these it is sometimes abundant and destructive. 

 Doctor P^'orbes has reported it from sorghum, broom corn, Indian 

 corn, Setaria, Panicum^ and wheat. Mr. Kelly first reported its oc- 

 currence on Panicum crus-galU, and in 190G I reared it through a 

 number of generations on Panicmn sanguinale, and collected it in the 

 field from blue grass, oats, and timothy, Mr. Paul Hayhurst, of the 

 Bureau of Entomology, U. S. Department of Agriculture, wrote me 

 of finding it on Setarla glauca. Thus, so far as known, Sipha flaoa 

 feeds only on plants of the grass family (Gramineai). In Europe 

 there are at present 8 or 9 known species of the genus Sipha^ and, 

 according to Del Guercio," all, with the exception of one species, 

 Sijjha hignonoi Maccli., feed only upon the grasses of the families 

 Graminese and Juncacese. Sipha hignome is probably not a typical 

 Sipha^ and it was originally doubtfully placed under the genus 

 Lachnus by Macchiati.^ In America two species {S. ruhifolil and 

 S. fava) have been placed under the genus Sipha. S. ruhifoUi is 

 found only on blackberry (Ruhus), but this species probably belongs 

 to an undescribed genus, and undoubtedly does not properly belong 

 under the genus Sipha of Passerini. 



Heretofore this aphis has never been positively reported outside of 

 Illinois, but this year (1907) Mr. Hayhurst sent me specimens from 

 Minnesota, Virginia, and Oklahoma, and wrote me that he found 

 it also in New York, West Virginia, and Texas. It seems likely, 

 therefore, that it is distributed over the United States, more or less 

 generally, east of the Mississippi Kiver. It will probably be found 

 to be more generally distributed in the South, because all of the 

 known facts regarding the distribution of this species, as well as of 

 the European species of Sipha, indicate that they are probably of 

 subtropical origin. 



Young hatching from eggs March 18 were reared to adults and 

 successive generations obtained. In one case the first young of the 

 first young was taken all the way through the series, 16 generations 

 being obtained. (Table X.) 



*' GuERCio, G. Del. — Coutribuzioue alia Couoscenza tiella Siplia Pass, ed alia 

 loro posizione uella Famiglia degli Afidi. <Redia, Fireuze, Italy, Vol. II 

 (1904), pp. 127-153. 



^ Macchiati, Luigi. — Fauna e flora degli Afidi di Calabria. <Bul. Soc, Ent. 

 Ital., Vol. XV (1883), p. 262. 



