194 EXPERIMENTAL FARMS 



8-9 EDWARD VII., A. 1909 



States to the south of our border. Actual specimens of this insect, Toxoptera grami- 

 num, Rond., were received from Emerson, Manitoba, but these had merely spread over 

 the border from an infestation a few miles to the south in Minnesota and did no 

 harm in our wheat fields. There weve, however, serious complaints of injury in Mani- 

 toba and the eastern part of Saskatchewan from the ordinary Grain Aphis, Macro- 

 siphtim granaria, Kirby, a somewhat similar insect but one which is easily distin- 

 guished from it by the venation of the wings when examined under a magnifying 

 glass. There a-ve, four plant lice which injure wheat in the west. (1) The Spring Grain 

 Aphis, or so-called ' Green Bug ' which for tiie most part attacks th^e leav^ of the 

 young plants, and which has the second vein from the tip of the upper wings only 

 once forked or divided, and the small honey tubes at the end of the body above, of a 

 pale colour with only the tips darkened. (2) The Grain Aphis, which has the second 

 vein twice divided and the tubes black. (3) Tlie Oat Grain Aphis, Sipliocoryne avence, 

 Fab., also called the European Grain Aphis, which in the winged form has the second 

 vein forked, but instead of being divided at the tip so that the first fork from the tip 

 leaves the main vein one-quarter of the way from the end, it is only about one-eighth 

 of the distance, thus leaving the cell at the tip of this vein very small. The tubes at 

 the end of the body are distinctly broader at the base than toward the apex. The eyes 

 are reddish as in the Grain Aphis and the front of the head is not pointed in which 

 it agrees also with the last named species. The two last named plant lice although 

 they occur upon the leaves of the small grains during part of their life-history are 

 much more apt to cluster together on the heads as soon as these are formed, while it 

 is stated that the Spring Grain Aphis only attacks the leaves. Prof. Washburn states 

 distinctly, ' Toxoptera was never found according to the reports of our field workers 

 on the heads of any of its food plants, differing in this respect from Macrosiphum 

 granaria which attacks the heads as soon as they appear.' (4) The Apple Aphis, Aphis 

 mali. Fab. This species does not feed the whole season on the plants of the various 

 small grains but migrates to them during the summer time from apple trees, the win- 

 ter being passsed in the egg condition on the branches of apple trees in a similar way 

 to that in which the Hop Aphis winters on plum trees. After four or five generations 

 on apple trees in the spring, winged migrants are produced all of which fly to the grain 

 fields and at once produce large numbers of wingless young, all of which are females. 

 These towards the end of the season produce perfect males and females, which, after 

 mating, deposit the winter eggs on apple trees. 



The injuries by the Spring Grain Aphis have been more pronounced in the 

 southern districts of the United States; but the species has spread northward in 

 injurious numbers almost to owe borders. The chief check on the excessive increase 

 of this pest in the United States has been the sudden appearance in large numbers 

 of a minute parasitic wasp, named Lysiphlehtis tritici, Ashm., which not only destroys 

 this grain aphis but also all other species found in grain crops. It is fortunately 

 present in large numbers in all the districts from which grain plant lice were sent 

 last summer. The injuries by the ordinary Grain Aphis, M. granaria, were in some 

 places severe, being reported in July, August and September. These injuries were 

 chiefly in the west. 



' Welwyn, Sask., August 26. — I send specimens of a green aphis and some heads 

 of wheat showing the way in which they feed. Seemingly they suck the sap out of 

 the base of the grain where it is attached to the stem. Is this the same as the green 

 bug they have in the Western States? They are doing the grain fearful damage, as 

 they are in millions. So far I have only seen it on breaking. I have not heard of 

 any other fields in this neighbourhood, and I only discovered them on my own three 

 days ago. — Ranald Stewart.' 



'Welwyn, September 10. — I send you some more wheat and bugs. I have found 

 no parasites. The bugs are not as plentiful as they were three weeks ago and summer 

 fallows seem to be free. I have just heard to-day that there are himdveds of ncres 

 about 30 miles northeast of here which are not worth cutting. Two farmers there 



