THE CANADIAN ENTOMOLOGIST. 77 



THE SPRING GRAIN APHIS OR "GREEN BUG." 



This aphis Toxoptera graminum Rond., must not be confused 

 with the wide-spread grain aphis Macrosiphum granaria Buckton, 

 formerly known as Siphonophora avencB Fab., which is destructive 

 from time to time in Canada. Toxoptera graminum has been found 

 in western Canada, but it has not as yet inflicted depredations of 

 so serious a character as have been recorded from time to time 

 since 1890 in the United States. The very destructive nature of 

 the "Green Bug," as it is popularly termed, in the United States 

 in 1907, in which year it was also recorded in Manitoba and Sask- 

 atchewan, led the United States Congress to make a special 

 appropriation for its investigation. These investigations have 

 been continued up to the end of 1911 and the Bureau of Entomol- 

 ogy of the United States Department of Agriculture have now 

 published a record of the entire investigation by F. M. Webster 

 and his assistant, W. T. Phillips (Bull. No. 110, Bur. Ent., U. S. 

 Dept. Agric, Washington, 153 pp., 48 figs., 9 pis., 1912). 



It is not possible within the compass of a short article to refer 

 in more than a brief manner to the varied and valuable results of 

 this study. The study is of unusual interest in that it afTords 

 results of value not only to the economic worker but also to the 

 embryologist and to the student of insect bionomics, all of which 

 results are necessary to a complete interpretation of this remark- 

 able insect's habits and depredations. 



South of the 35th parallel it appears to be permanently 

 viviparous and to breed without the appearance of the sexes. It 

 is unable to survive hot and dry conditions in the Southern 

 States. In Indiana the overwintered eggs hatch from the end of 

 March to about April 10th giving rise to wingless stem-mothers 

 which pass through five instars. These stem-mothers reproduce 

 viviparously producing wingless viviparous females and winged 

 viv'iparous females. 



The great fecundity of the aphids, due to their viviparous 

 habits, is well known and the results of the authors' study of the 

 progeny of single lines are of great interest in this connection. In 

 Indiana the eggs hatched on March 27th, and the first-born aphids 

 produced twenty-one generations before the adult ovipositing 

 females appeared in November; the last born females produced ten 



March, 1913 



