THE OAT APHIS. 



malaceje — continued. 



Ninebark, Opulaster opulifolius. 1 



AMYGDALACEyE. 



Plum, Primus sp. 



Choke cherry, Padus virginiana 



Wild black cherry — 



Padus serotina 



Padus* padus 



Pear, Pyrus communis 

 Hawthorn, Crataegus coccinea, etc. 

 American mountain ash, Sorbus 



americana 

 Quince, Cydonia vulgaris 

 Double-flowering crab apple (Mains 



sp.) 

 Wild crab apple (Mains sp.) 



In addition to the foregoing list of food plants, Mr. Theodore 

 Pergande lists dogwood (Cornus sp.), shepherd's purse {Bursa bursa- 

 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 

 avence. 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 avence, 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 * discusses, under the name 

 Siphonophora avenrn, at least two 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 avence, Fabricius." 



3 Eighth report of the State entomologist on the * * * insects of the State of 

 Illinois, 1879, p. 51-55. "Siphonophora avenm, Fab." 



*U. S. Sec. Agr. Rpt. for 1889 (1889), p. 348. 



