8 



Pflanzenkrankheiten, Beitrage zur landwirthschaftlichen Insekten- 

 kunde, Vol. IV, p. 4. 1894). He says: 



Fifteen or sixteen years ago I always raised excellent oats on a field bordering a 

 meadow; all of the plants were of a strong and healthy growth, and about one meter 

 in height. Later, however, notwithstanding heavy manuring, the stalks became 

 gradually more slender and lower, and the crop of the grain so scant as not to pay 

 for cultivation. Happening once to inspect the grain during summer at the proper 

 time, I found that the cause of the decline was a plant-louse, which Dr. Geza v. Hor- 

 vath, at Kecokemet, in 1884, discovered to be the cause of "'reddening" of the leaves 

 and the total destruction of the young plants, and which proved to be the grain aphid, 

 Toxoptera graminis Kond. 



It occurred to me that, by abandoning the common or Bauern oats and replacing 

 it by finer and stronger varieties, they might be able to successfully withstand the 

 attacks of the Toxoptera. I was, however, much mistaken. I planted on some of 

 my best fields adjoining the meadow a row of triumph oats, Anderbeck oats, and the 

 common Bauern oats, and found that lice showed a decided preference for the finer 

 varieties with broad, bandlike, and juicy leaves, particularly the triumph oats. Of 

 this variety absolutely nothing was left; all of the plants were destroyed before they 

 reached a few inches in height; the whole field was completely ruined as if it had 

 been swept by fire. Anderbeck oats resisted somewhat, though not much better, 

 whereas the common oats showed the best results, of which at Least half a crop was 

 obtained. 



I am of the opinion that this invasion of the aphides had its origin in the meadow, 

 because the trouble began first along the edge of the meadow and spread gradually 

 to the middle of the field. Unfortunately all of my fields suitable for the cultivati m 

 of oats are in the immediate neighborhood of meadows or along patches of grass, 

 while the more distant fields are of a sandy nature and can only be used for cultiva- 

 tion of rye. corn, etc.. which renders a comparison impossible. 



The consequences, therefore, were that I had to reduce the cultivation of oats to 

 a minimum and to replace it with fodder corn, turnips, clover, etc. 



Professor Sajo (p. 150, lor. cit.) says that this species 1ms probably 

 nowhere else, except in Hungary, shown itself to be so destructive, 

 but that in Hungary it is one of the most destructive enemies of barley 

 and oats. lie states that its destructive habits were first described by 

 Dr. G. v. Horvath. who discovered it to be the cause of the reddening 

 of the oats at Kecshemet, and that during the following- years similar 

 complaints were reported from the provinces of Bacs-Bodrog, Borsod, 

 and Csanad. 



The latest contributions regarding the food plants of this species 

 were published by Dr. Giac. Del Guercio (Nuove Relazioni R. Staz. 

 di Entom. Agraria, Firenze, serie prima, No. 2; Prospetto Dell' 

 Afidofauna Italica, p. 145, 1900) with the statement that this plant 

 louse is found in considerable numbers on THticum vulgare, Hordeum 

 vulgare, Avena sat iva, Zea mais, Dactylis glomerata, Bromus sp., and 

 Lolium perenna. 



HISTORY OF THE SPECIES IN AMERICA. 



The earliest record in the possession of the IT. S. Department of 

 Agriculture of the presence of this pest in the United States dates 



