265 



Cbiddle (N.). Further Observations upon the Habits of the Western 

 Wheat-stem Sawfly in Manitoba and Saskatchewan. — Agric. Gaz,. 

 Canada, Ottawa, iv, no. 3, March 1917, pp. 176-177. 



This paper supplements a former one on the western wheat-stem 

 sawfly {Cephus occidentalis) [see this Revieiv, Ser. A, iii, p. 630]. This 

 insect breeds in its native state chiefly on wild grasses belonging to 

 the genus Agropyron. On sandy soils the grass most commonly infested 

 is ^. richardsoni; on richer soil, especially in more western latitudes 

 where this grass is less prevalent, it may be found more especially on 

 A. smithi, a grass which closely resembles A. repens (couch grass). 

 A. smithi is a common grass on the western prairies and is of consider- 

 able economic importance. In very dry years its stems seldom attain 

 the size sufficient to accomodate the sawfly larvae, but under ordinary 

 weather conditions about 30 per cent, of these are available as breeding 

 places, while under abnormal ones 90 per cent, may become suitable for 

 this purpose. The importance of this sawfly as a pest therefore depends 

 directly upon the rainfall. Though the sowing of cereals, especially 

 wheat and rye, has placed an unUmited supply of food at the disposal 

 of this pest, yet it sometimes gradually disappears from cultivated 

 crops, as if they were not wholly suitable to its requirements. 

 A. repens is even more suitable as a food -plant for C. occidentalis, 

 as, under normal conditions, it provides nearly 100 per cent, of stems 

 in which it may breed, while it is a weed of the first rank. Species 

 of lyme grass {Elymus) are also food-plants of great importance, 

 especially as they are perennials. 



One control measure consists in the sowing of a trap-crop of either 

 wheat or rye, as early as possible in the spring, between the last year's 

 infested area and the new crop. The sawflies emerging from the old 

 stubble in June will breed upon this trap-crop, which can be either 

 ploughed up or cut down in July and the infested stubble destroyed 

 by burning. 



Spraying Experiments.— ^^rjc. Gaz. Canada, Ottawa, ix, no. 3, March 

 1917, pp. 193-214. 



Under this heading are included a number of papers from the 

 different provinces of the Dominion emphasising the good results of 

 spraying work conducted at the various experiment stations in Canada ; 

 the greater part of the information given has already been noticed 

 in this Review. 



Back (E. A.). The Mediterranean Fruit Fly. — Mthly. Bull. Cal. State 

 Commiss. Hortic., Sacramento, vi, no. 3 & 4, April 1917, 

 pp. 69-80, 5 figs., 2 plates. 



The Mediterranean fruit-fly {Ceratitis capitate) is found in South 

 America, Africa, southern Europe, Asia Minor and Australia. Though 

 it does not yet occur in the North American continent, its presence in 

 Bermuda and the Hawaiian Islands is a constant source of danger. 

 The object of this paper is to call attention to the seriousness of the 

 situation threatening the more tropical portions of the United States, 

 and to show that everything possible is being done by the Federal and 



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