212 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 7 



Euthrips nervosus Uzel was also found. I was unable to find other rec- 

 ords of this type of thrips injury at the time, except one which Mr. 

 F. M. Webster showed me in 1910 in the Bureau of Entomology of 

 the United States Department of Agriculture, Washington, D. C; in 

 this case A. striatus was recorded as injuring oats. 



Since commencing this study several records have been given in 

 European literature of thrips injury to cereals. Korolikoff (1910) 

 has investigated a number of species of thrips injurious to cereals and 

 grasses in Russia, in the neighborhood of Moscow. Stranak (1912) 

 has investigated the species of thrips which caused unusual injuries to 

 grain crops in Bohe-nia in 1912. Rye was most seriously affected, 

 from 25 to 100 per cent, being attacked, wheat varied from 5 to 70 per 

 cent., barley varied from 5 to 40 per cent., and oats appear to have been 

 the least attacked, varying from 2 to 20 per cent. On the average, 

 29 per cent, of the spikelets were wanting and in the remainder of the 

 injured spikelets the development of sound grain had been inhibited. 

 A number of species of thrips were found to be responsible for the 

 damage. ^ 



In discussing "White-heads" or "Take-all" of wheat and oats ^ the 

 writer of the article states that much shrivelling of the grain and bleach- 

 ing or silvering of the inflorescence in cereals and wild grasses is due to 

 the activity of Thrips cerealium Halid. Zimmermann (1911) refers 

 to Thrips cerealium Halid. occurring on oats, and his observations in 

 Europe confirm my own made at Ottawa, namely, that early flowering 

 varieties are less injured; most injuries being found on the later vari- 

 eties where the emergence of the inflorescence is delayed. Miss Orme- 

 rod (1892) also referred to the shrivelling of the grain caused by the 

 cereal thrips. Taschenberg (1880) records the injury caused by T. 

 cerealium. Halid. to the developing grain of wheat, rye and barley. 



Fletcher recorded the occurrence of "White-top" in 1888 in June 

 grass {Poa pratensis) and also in timothy {Phleum pratense) and couch 

 grass {Triticum repens). While " White-top " in wheat is usually caused 

 by the wheat-stem maggot {Meromyza americana Fitch) I have found 

 specimens of such white-top in wheat which were undoubtedly caused 

 by thrips. Comstock (1875) was the first to refer to "Silver top" or 

 "White-top" injury by Anaphothrips striatus to June grass and timo- 

 thy, and other entomologists including Hinds (1902) have subsequently 

 recorded similar observations. Fernald and Hinds (1900) in their 

 account of the grass thrips, A. striatus, refer to its extensive injuries to 

 June grass. 



In all the accounts of the injury of Anaphothrips striatus to June 



» Jonm. Board of Agriculture (London), Vol. 19, p. 1020, 1913. 



