18 THE SPEIXG GRAIN-APHIS OR - GBEEN BUG. 



hymenopterous parasite, ApMdius sp., and larvae and adults of a 

 coccinellid, Adalia jiavomaculata De G. ; both of which were observed 

 destroying the aphidids. Under date of October 1, 1910, Mr. C. P. 

 v. d. Merwl, assistant biologist of the same department, stated that 

 another outbreak of the pest had taken place that spring and con- 

 siderable damage had been done. In this communication the state- 

 ment was made that the writer had personal knowledge of the 

 occurrence of the species during the past 20 years, and that farmers 

 had stated that they had always known of its occurrence in that 

 country. It had, however, become seriously destructive during 

 recent years and at that time farmers were being forced to give up 

 growing wheat extensively on account of its ravages. 



In the Agricultural Journal of India x Mr. H. Maxwell-Lefroy, 

 government entomologist of British India, stated that the wheat 

 aphis (Toxoptera graminum) seeks shelter in the depths of the grass 

 roots; in different ways insects adapt themselves, but these had 

 probably done it gradually, moving in from cooler to hotter areas 

 step by step. From the illustration of this insect accompanying this 

 statement and from specimens later submitted by Mr. Maxwell- 

 Lefroy, it has been found impossible to determine the species involved 

 as Toxoptera graminum. 



On November 25, 1910, Mr. William Sewall, of Xjoro, British East 

 Africa, called at the office of this bureau to complain of the ravages 

 of a green louse or fly which attacked and destroyed wheat on his 

 farm in the above-named locality, situated almost directly on the 

 equator in a prairie-like country at an elevation of 7,000 feet above 

 sea level. A communication was received from Mr. Sewall bearing 

 date of August 22, 1911, accompanied by specimens, in which he 

 stated that the ravages now extend over an area of 700 acres. He 

 also stated that his neighbor, Lord Delamere, who had not been 

 troubled previously, experienced severe losses over an area of about 

 4,000 acres. The specimens accompanying Mr. Sewall's letter have 

 been determined as Toxoptera graminum by Mr. J. T. Monell. 



With these records of the known and probable distribution of 

 Toxoptera graminum, it does not seem improbable that if the minute 

 insects of the family Aphididse were carefully studied this species 

 would be found generally diffused throughout the temperate and 

 tropical regions of the world. 



KNOWN DISTRIBUTION IN THE WESTERN HEMISPHERE. 



With reference to the distribution of this insect in the Western 

 Hemisphere (see fig. 4), it can be said that it has only been studied in 

 the United States. Its occurrence in western Canada is well established. 

 On the south it is known along the Mexican border from the Gulf of 



» " Imported insect pests." Agricultural Journal of India, vol. 3, part 3, pp. 243-244, July, 1908. 



