Some years ago I examined and compared a number of specimens, 

 labeled by Fitch, and now contained in the collection of the United 

 States Department of Agriculture, both of his A. mall and his A. avenae, 

 as well as a number of specimens of A. averts? kindh T sent me by Dr. 

 H. Sckouteden, Brussels, Belgium, all of which confirmed my opinion 

 which is that the American apple louse and the grain louse are identi- 

 cal, and that the European A. mail, of which the first American colo- 

 nies were found in the spring of 1897, is quite a distinct species, not 

 even generically identical with the genuine grain louse of Europe, nor 

 with the grain louse described by Thomas as Sijjhonophom avense. On 

 further examination and comparison of the insect under consideration, 

 I have concluded that it belongs to the genus Siphocoryne of Passerini, 

 described in "Aphidida? Italica?'' (p. 52, 1863). He there states that 

 the nectaries are clavate, while otherwise it is similar to Aphis, plac- 

 ing with it but three species; failing, however, to discover the clavate 

 character of the nectaries in avena?, which occasionally exhibits this 

 character but faintly, so as to make them appear cylindrical and was 

 therefore still retained b\ T him in the genus Aphis; whereas in the true 

 genus Aphis the nectaries are always more or less distinctly tapering. 



According to my own observations, after the migrants had been 

 transferred from apple and Crataegus to grain and grasses, I have 

 found a certain range of variation in the comparative length in the 

 joints of the antenna?, as well as in the nectaries of the progeny of 

 the apple louse, the extreme forms of which may, easily induce super- 

 ficial students to consider them as distinct. Large series, however, 

 of the various forms, more or less due to the season or abundance of 

 food, have convinced me that all of them belong, to but one species. 

 Some of the most constant characters of this insect are the compara- 

 tively small or minute terminal fork of the front wings, which fre- 

 quently varies considerably in the same specimen; the more or less 

 strongly pronounced tuberculation of joints three and four and fre- 

 quently also the fifth joint of the antenna?, and the clavate character 

 of the nectaries, which frequently becomes rather pronounced. 



Observations thus far made tend to show that the species is biennial 

 and that the progeny of the spring migrants from the apple subsist 

 almost exclusiveh T upon various grains and grasses until the fall of 

 the second year, when a generation of return migrants makes its 

 appearance. The earliest ones of these produce the sexual females, 

 whereas the others, appearing several weeks later, are the true males, 

 thus closing the cycle of existence of the species. These observations 

 s"how also that the progeny of the migrants from the apple are rarel} T 

 seen during the heated term, and that most of them station themselves 

 close to the base of the plants; though I have, on one occasion, also 

 found a colony of Siphocoryne avenx, including the winged form, 

 about the middle of August, on the leavesof Panicum sa/tiguinale^ in 



