THE OAT APHIS. 
malace^e — continued. 
Ninebark, Opulaster opulifolius. 1 
AMYGDALACE^. 
Plum, Primus sp. 
Choke cherry, Padus virginiana 
Wild black cherry — 
Padus serotina 
Padus< padus 
Pear, Pyrus communis 
Hawthorn, Gratwgus coccinea, etc. 
American mountain ash, Sorbus 
americana 
Quince, Cydonia vulgaris 
Double-flowering crab apple (Malus 
sp.) 
Wild crab apple (Malus sp.) 
In addition to the foregoing list of food plants, Mr. Theodore 
Pergande lists dogwood (Cornns sp.), shepherd's purse (Bursa hursa- 
pastoris), and burdock (Arctium minus) ; but in each case he notes 
that it is, or evidently is, accidental. 
Although this species, as shown, has a large number of available 
host plants, it is more often to be found in the fall and spring on 
wheat, blue grass, apple, and pear. In early summer it is frequently 
found on oats, wheat, blue grass, and, previous to June, on apple and 
pear, and in later summer on volunteer wheat and oats and on blue 
grass. 
INJURIES AND METHOD OF WORK. 
Probably no other species among the plant-lice has been so com- 
pletely confused in literature as the one under discussion. Numerous 
reports of injury to apple^ wheat, and oats have been made since its 
discovery in 1851, but in most instances there seems to have been some 
confusion in the species, and it is impossible in such cases to deter- 
mine just which of several species may have been responsible for the 
damage. Thus in 1865 Fitch 2 described and figured a Macrosiphum 
on wheat, although some of his observations doubtless refer to Aphis 
avenw. In 1879 Thomas 3 reported a plant-louse which damaged 
wheat considerably in Illinois in 1866 and again in 1876, but in his 
description he has confused two species, Macrosiphum granarium 
and Aphis avenw, and there is no means by which the particular 
species troubling grain in the years mentioned can be identified. 
Again, Kiley in his report for 1889 4 discusses, under the name 
Siphonophora avence, at least tw T o species, and the facts relating 
to life history, injuries, parasites, etc., refer to more than one species; 
consequently this data must be ignored for the present, although the 
colored figures and probably most of the data contained in the arti- 
cle refer to Macrosiphum granarium rather than to the species under 
discussion. The same must be said of many other references to grain 
1 Recorded here for the first time. 
2 Sixth report on the insects of N. Y., 1865, p. 91-97. "Aphis avenw, Fabricius." 
3 Eighth report of the State entomologist on the * * * insects of the State of 
Illinois, 1879, p. 51-55. "Siphonophora avenw, Fab." 
*U. S. Sec. Agr. Rpt. for 1889 (1889), p. 348. 
