247 



these reports they usually i^roved to be Toxoptera. At Lafayette this 

 was by far the most abuudant species wintering ov^er in the wheat 

 fields, and examinations in April showed them to have survived the 

 winter in great numbers. They did not a.i)pear to increase rapidly, and 

 I liad ceased to anticipate trouble from them, when early in June let- 

 ters from the southern part of Indiana gave the information that the 

 grain Aphis was appearing in the wheat tields precisely as it had done 

 the previous year, and was also ravaging the oat fields, A visit to 

 Posey County on the 11th day of June revealed the true state of affairs. 

 There were Siphonophora avenw on the wheat in considerable abun- 

 dance, and many also on the oats, but the number on the latter grain 

 was no comparison to those of the Toxoptera. Not oidy were the 

 larger leaves covered with them in many cases, but the tender unfold- 

 ing leaves also, while there were myriads of the brown parasitized 

 females everywhere on the plant. The oat crop was there a total fail- 

 ure, many tields being at that time as brown as though the entire 

 growth of plants had been winter-killed. There was no lack of proof 

 that the damage, so far as due to insect attack at all, had been done 

 by this species. 



From notices appearing in Illinois and Missouri jiapers, I am 

 inclined to the opinion that the Toxoptera was equally abundant in 

 portions of these States. In the extreme southern portions of Indiana 

 the oat crop was a total failure; in many cases I was at a loss to 

 account for this destruction, as its magnitude did not correspond to 

 the numbers of the Toxoptera, notwithstanding its numbers were enor- 

 mous. A solution of the problem, however, came from an unexi)ected 

 quarter. Prof. B. T. Galloway, Chief of the Division of Vegetable 

 Pathology, had, during the summer, discovered a bacterial disease in 

 the oats plants, of which I had no knowledge, and his paper on a ''New 

 Disease of Oats" read at the Indianapolis meeting of the American As- 

 sociation for the Advancement of Science,* relieved me from my dilem- 

 ma. While the Toxoptera can not be held entirely responsible for the fail- 

 ure of the oats crop during that season, as serious damage occurred where 

 the insects were not sufficiently abundant to be noticeable, yet they cer- 

 tainly aggravated the work of destruction in several States, and in 

 southern Indiana, at least, greatly emphasized the effect of this dis- 

 ease, showing us clearly that the species may in future prove a serious 

 pest to the oats crop. 



The young and apterous agamic females may be confused with the 

 true Grain Aphis, Siplionophora aveme^ by casual observers, but the 

 winged female has the cubital vein of the wing but once forked, thereby 

 disthiguishing it from all others of the subfamily Aphidiuai. These 

 Toxoptera are great favorites of ants, while I have never yet observed 

 an ant in attendance on Siplionophora avenw, Prof. A. J. Cook notwith- 

 standing. 



* Prelimiuary notes on a new and destructive oat disease, by B. T. Galloway and 

 E. A. Southworth. The Journal of Mycology, vol. vi, no. 2, p. 72, September, 1890. 



