I i „__--„ -r,,.,.-. >> 



84: THE SPEIXG GRAIN-APHIS OK GEEEX BUG. 



Under date of May 17, 1907, also at Wellington, Kans., Mr. Ainslie 

 made an interesting record as follows: * 



Yesterday, the 16th, the air was full of Toxoptera rising on wing, but the breeze 

 was light and they had no chance to travel far. If the wind had favored their flight 

 they must have carried parasites with them as guests, by the myriad, for many of 

 them, probably the major part, were parasitized. [The temperature at Wichita 

 ranged from 44° to 82° F.] 



On the same day the senior author, in company with Prof. E. A. 

 Popenoe, in driving about the country in the vicinity of Manhattan, 

 Kans., during the afternoon found that they were in the midst of 

 swarms of winged Toxoptera; frequently a number of individuals 

 might be noted crawling about over their hats and coats and to an 

 annoying degree traveling over their faces. Two days later, the 

 senior author observed both winged Toxoptera and Aphidius crawl- 

 ing about on the inside of the windows of a Pullman car in which he 

 was traveling over the Santa Fe, crossing central Kansas. 



At Piano, Tex., June 4, 1909, Mr. Urbahns learned of a most 

 interesting migration reported to him as having taken place two 

 days before. A farmer, Mr. Foreman, reported to him that ''green 

 bugs" were observed flying east, probably coming from out of a 

 very badly infested wheat field, moving with the evening breeze. 

 In this case there was clearly a rapid disappearing of the food supply, 

 precipitating a development to winged adults that were probably 

 forsaking the fields for some other locality affording them a greater 

 abundance of food. It would appear," then, that the influence of 

 winds is more or less dependent upon several other phenomena. 



With the natural advance of spring from the South, there would 

 be a continually decreasing supply of fresh, tender, succulent food 

 in the South, while to the Xorth this condition would be reversed. 

 Therefore, with winged viviparous females developing with increas- 

 ing abundance along the area of a certain latitude, such winged 

 females as were carried south or backward over an area already ren- 

 dered barren of food would consequently perish. On the other 

 hand, those females that drifted or made their way northward would 

 encounter a continually increasing fresh supply of food; therefore 

 they might be said to follow along with the advance of the spring 

 from the South far into the North, until overtaken by their natural 

 enemies. Then, too, south winds are associated with a warm tem- 

 perature and north winds with the reverse, as will be seen from 

 Tables IV- VIII, furnished by the United States WeatJier Bureau. 

 Another factor that must not be lost sight of is that after about the 

 latitude of southern Kansas and Missouri is reached wheat ceases 

 to be the food plant for Toxoptera in spring, and spring oats takes 

 its place in this respect. 



