226 EXPERIMENTAL FARMS 



2 GEORGE V.,wA. 1912 



Tins makes 5 gallons of 80 per cent, emulsion. The soap should be cut up and 

 dissolved in the requisite amount of water by boiling, adding water to make up for 

 that which is lost by evaporation. The soap solution and oil are mixed thoroughly to 

 form an emulsion. This stock solution will keep, and for use a 25 per cent solution 

 should be made by using one part of the stock solution to 2£ parts of water. Beau- 

 mont oil is recommended as being less injurious than the heavier varieties of oil, 

 and not so volatile as the lighter oils. Cattle should be sprayed with a 20 to 25 per 

 cent, emulsion every fortnight. Every part of the animal, especially the inside of the 

 thighs and elbows and dewlap should be thoroughly sprayed. Horses should be freed 

 fcy picking. Certain species of ticks carry organisms of serious diseases, as for example 

 the tick Margaropus annulatus of the southern United States, which is the carrier of 

 the organism causing the dangerous Texas Fever. Redwater Fever is also transmitted 

 by ticks. 



THRIPS ATTACKING CEREALS. 



During the last few years frequent inquiries have been made in reference to the 

 ' blighted ' appearance of the heads of oats and wheat and a number of samples of the 

 injured plants were received. Oats were chiefly attacked with the production of the 

 characteristic ' silver top ' or ' white top ' appearance. Most of the reports of injury 

 were received from Alberta and Saskatchewan. One correspondent from Vancouver 

 Island, B.C., stated that over 50 per cent of a fourteen acre field of oats were attacked 1 . 

 On heads of oats received from Saskatchewan from fifty to seventy per cent of the 

 ears were destroyed and had the typical bleached appearance. Mr. A. Mackay, the 

 Superintendent of the Experimental Farm at Indian Head, Sask., informs me that he 

 has noticed the ' silver-top ' on oats for several years, but especially during the last 

 year or two. 



We were unable to obtain specimens of the insects from most of the samples as 

 they were dry on arrival here, owing to the long journey and the few insects obtained 

 were too dessicated to make their identification possible. This species may be the 

 Grass Thrips (Anaphothrips striatus Osborn), and Mr. F. M. Webster, of the United 

 States Bureau of Entomology showed me a record which he had of this species attack- 

 ing oats. The Grass Thrips produces ' white ' or ' silver top ' in a number of grasses, 

 especially in Kentucky Blue Grass (Poa pratensis) . Dr. Fletcher recorded the occur- 

 rence of ' white top ' in 1888 and 1892 in P. pratensis and also in Timothy (Phleum 

 pratense) and Couch Grass (Triticum repens). 'White top' in wheat is usually caused 

 by the work of the Wheat-stem Maggot (Meromyza amsricana Fitch), but the speci- 

 mens of white top in wheat which we received were undoubtedly caused by thrips. 



Other species attacking oats axe^olothrips fasciatus L. (which also attacks wheat, 

 grasses and weeds) and Limothrips cerealium Hal. It is not unlikely that these 

 species occur in Canada. 



These insects are minute and in consequence generally escape observation. The 

 Grass Thrips (A. striatus) measures about one-sixteenth of an inch in length and is 

 yellow or brownish yellow in colour. The adults are provided with four narrow wings 

 fringed with long hairs and are very active. There is, however, considerable variation 

 in the possession of wings and in the condition of the same fn this peculiar family 61 

 insects. Their mouth parts are adapted for both sucking and biting, but they appear 

 to take most of their food by sucking the juices of the plants. According to Hinds* 

 the life history is briefly as follows: The females continue to deposit their eggs on 

 the leaves of the grass and the young develop through the fall until the snow covers the 

 ground. The adults hibernate and appear to be able to withstand exposure to tempera- 



* Hinds, W. E.. ' Contribution to n Monograph of the insects of the order Thvsanoptera 

 inhabiting North America.' Proc. U.S. Nat. Mux. Vol. 26, pp. 79-242, 11 pis, 1902." 



