34 the COLORADO EXPERIMENT STATION 
louse as being almost “polyphagus,” on account of its feeding 
upon so many different plants. 
In America this louse has also been reported under different 
names upon the peach, plum, cherry and man succulent plants, 
including several of our garden vegetables. The Rhopalosiphum 
solani of Thomas, occurring in abundance upon potatoes in Illi¬ 
nois; the Siphonophora achryantes of Monell, and the Myziis 
malvae of Oestlund* are almost certainly this persicae of Sulzer, 
which was described nearly a century and a half ago. Since arriv¬ 
ing at the above conclusions* a letter has been received from Dr. 
N. Cholodkovsky of St. Petersburg, to whom specimens of this 
louse were sent and which were determined by him as being the 
persicae of Sulzer which he considers identical with the dianthi of 
Koch. 
NAME AND LIEE HISTORY 
There are two main reasons why this insect has been described 
under so many different names. It has a habit, which is not uncom¬ 
mon among the plant lice, of spending the fall, winter and spring 
of the year upon certain trees and shrubs, and the remainder of the 
year upon succulent vegetables. The winged form occurring upon 
the trees in the spring of the year (Plate II, Fig. 8) has its cornicles 
cylindrical in form while the winged individuals occurring upon 
succulent vegetation during the summer and fall, and those that 
return to the peach and other trees in September and October, 
(Plate II, Fig. 9) have their cornicles moderately swollen. The 
latter type of cornicle puts this louse into the genus Rhopalosiphum, 
while the former type of cornicle with the swollen antennal tubercles 
and first antennal joint, puts it into the genus Myzus. The other 
reason for the numerous names is its feeding upon a very wide 
range of plants. 
So we are unable to avoid the rather sweeping conclusion that 
the green peach louse with its cylindrical cornicles, its pink egg- 
laying females in the fall and similarly colored stem-females in the 
early spring, is only the tree form of the green louse with club 
shaped cornicles that is so abundant in green-houses upon carna¬ 
tions, snapdragons, lilies, and many other flowering plants and 
out of doors cabbage, cauliflower, radish, turnip, potato, and a host 
of other vegetables, both wild and cultivated, which has been des- 
* The Rliopalosiplium sonclii of Oestlund, which, in “Synopsis' of the 
Aphididae of Minnesota,” he seemed inclined to give up to Rliopalosipliiuii 
diantlii of Shrank, is probably a good species. At least, the native Sonchiis 
growing in the vicinity of Port Collins is badly infested with a Rhopalosi- 
plium that is certainly distinct from the louse here discussed, and it fits 
In every particular the description given by Professor Oestlund for 11 . 
sonclii. 
* See Journal of Economic Erut., Vol. I, No. 2, p. 84. 
