1909] Toxoptera graminum and its Parasites 69 



In August, 1907, at the meeting of the International Society of 

 Zoologists in Boston, and, later, also in Washington, I had the 

 good fortune to meet Dr. Horvath and from him learned that the 

 species had been found in Siberia on graminacese. 



For two or three years past, grain in the Orange River Colony, 

 South Africa, has been seriously affected by a species of Aphis, 

 we having received several complaints of these invasions from 

 Mr. H. Neethljng, at that time. Chief of the Horticultural and 

 Biological Division of the Department of Agriculture at Bloem- 

 fontein. It was only within the last few months, however, that 

 we were able to secure specimens of these aphids for identification 

 and, surprisingly enough, they prove to be Toxoptera graminum. 

 With these were a number of individuals of a species of Lysiphle- 

 bus, allied to the one that is so efficient in holding the pest 

 in check in America. This gives us records of the occurrence of 

 the species in Europe, Asia and Africa. 



OCCURRENCE IN THE WESTERN HEMISPHERE. 



The earliest information we have of the occurrence of Toxop- 

 tera graminum in America is in the year 1882, when it was received 

 at the Department of Agriculture, but sad to say there is no 

 record as to where the specimens came from. Late in June, 1884, 

 it was found sparingly on wheat in the vicinity of Cabin John, 

 a short distance north of Washington, and, about the same time, 

 I found it infesting wheat plants in some breeding cages where 

 some experiments were being carried on by myself at Oxford, 

 Indiana, about one hundred miles southeast of Chicago, Illinois. 

 Nothing more was heard of the species until 1890 when a very 

 serious and destructive outbreak occurred in the West, extend- 

 ing from northern Texas to Missouri and central Indiana. Cur- 

 iously enough there was little complaint from the territory east 

 of the Appalachian mountain system, even where considerable 

 wheat and oats were being at that time grown. Again, we have 

 a period of eleven years without noticeable injuries from this pest ; 

 then, in 1901, there came the most destructive outbreak that had 

 occurred up to that time, but in this instance depredations did 

 not extend farther north than central Oklahoma, though planters 

 in South Carolina afterwards reported "green lice" as having 

 been very abundant on oats during the spring of that year. 



In March, 1903, there was an incipient outbreak of the species 

 in northern Texas. But this seems not to have extended north- 

 ward beyond the Red River and was overcome by parasites in 



