THE SPRING GRAIN-APHIS OR ' ' GREEN BUG. ' * 27 



THE OUTBREAK OF 1907. 



(Fig. 5, p. 20; Diagram V, p. 28.) 



The outbreak of 1907 was by far the most serious and widespread 

 that has occurred in the United States up to the present time. Start- 

 ing in east-central Texas, the invasion swept northward and east- 

 ward, covering a somewhat fan-shaped area, through Oklahoma, 

 Kansas, northwestern Arkansas, Missouri, and across Illinois to 

 within 60 miles of Chicago. Though possibly not doing so much 

 damage in the Ohio Valley as in 1890, it extended westward through 

 Oklahoma and Kansas into southeastern Colorado. While not 

 especially injurious to oats and not at all to wheat in the States of 

 Nebraska, Iowa, Minnesota or the Dakotas, the late Dr. James 

 Fletcher states that in Canada it actually did some damage in Sas- 

 katchewan. Less damage was probably done in Indiana ana" Ohio 

 than in 1890, though the ravaged area in general followed the ground 

 covered by the previous outbreaks ; in this latter case the northeastern 

 terminus of the seriously ravaged area appeared to be confined more 

 closely to the upper Mississippi River and Illinois River valleys than to 

 that of the Ohio River, thus sweeping more broadly to the northward. 

 On the Atlantic coast fall oats were destroyed or badly injured in 

 South Carolina, and both wheat and oats in western North Carolina. 

 In Virginia, Kentucky, and Tennessee neither grain was, as a rule, 

 seriously damaged. The areas shown in figure 5 indicate all injury, 

 even though slight, in occasional and widely separated fields. In 

 the valleys of the upper Missouri River and the Red River of the 

 North there was little or no injury, and it seems doubtful if the pest 

 occurred in that section prior to this outbreak. 



Forebodings of trouble from this pest came as early as November 

 and December, 1906. According to copies of Mr. Sanborn's notes, 

 as placed at our disposal by Prof. A. F. Conradi, the species was sent 

 to the Texas experiment station from Howe, Grayson County, Tex., 

 where it occurred on oats, as early as November 14, 1906, and one 

 day earlier from Allen, Collin County, of the same State, where it 

 was present in great numbers attacking volunteer oats plants. On 

 December 22, 1906, it was sufficiently abundant about Piano, Collin 

 County, Tex., to destroy oats in patches in the fields, its natural 

 enemies at the time being in a dormant condition because the tem- 

 perature had not reached and remained at a degree that would 

 render them active. During January and February, 1907, these 

 conditions continued, the Toxoptera breeding and spreading unre- 

 strained by its enemies, so that the area over which it was becoming 

 destructive continually increased. 



Rumors of injuries by this pest came to us early in January, 1907, 

 from east-central Texas, where the " green bugs' ' were reported to 

 Mr. W. D. Hunter, in charge of cotton boll weevil investigations of 



