September, 1921 



SCIENTIFIC AGRICULTURE 



21 



the maintenance of an orcliard survey has 

 been reduced in New Brunswick by about 

 sevent3'-five per cent. 



With the Brown-tail Moth problem there 

 was also a Gipsy Moth problem. This in- 

 sect had also become established in the New 

 Enj?land States and its parasites had been 

 loft in its native Europe. Tlie parasites 



nursery stock in about 1885 and it is now 

 scattered over Southern British Columbia, 

 including the fruit-growing areas of Van- 

 couver Island, the Lower Fraser Valley and 

 the Okanagan valley. It was found to be 

 increasing rapidly in the last-mentioned 

 place and not a single one of the useful 

 mites was found in material collected from 

 representative places throughout British 

 Columbia. The Scale had found its way 

 into British Columbia but its foremost nat- 

 ural enemy had been unable to follow. 

 Some of the mites were immediateh' intro- 

 duced from New Brunswick and the results 

 awaited with considerable interest. Two 

 years later the mites had become so num- 

 erous that they had destroyed all the Oys- 

 ter Shell Scales within distance of the most 

 important colon}-, which was liberated at 

 Vernon in the Okanagan Valley. 



Another insect that has given a good 

 deal of trouble is the Oak Looper that per- 

 iodicalh' defoliates the oak trees which have 

 so much to do with real estate values in 

 the neighbourhod of Victoria. A preda- 



,. . * .nv, •■ • , . ceous beetle has been introduced, but it is 



Hemisarcoptes. — This microscopical creature ji^ , , • i i 



makes a living by feeding upon eggs of the**too early as yet to know With what results. 



Oyster Shell Scale. 



i 



were the same trio that attack the Brown- 

 tail Moth and as these are now established 

 at all strategic points in Canada we can 

 wait for the coming of the Gipsy Moth into 

 Canada, confident that it will not occa- 

 sion with us the million dollar losses that it 

 occasioned in the New England States be- 

 fore the introduction of its natural ene- 

 mies. 



The next project had to do with the 

 Oyster Shell Scale. Like the above-men- 

 tioned insects, this pest of orchard trees 

 came to us from Europe and for the first 

 fifty years it did untold mischief, destroy- 

 ing a very large number of apple orchards 

 north of the Mason-Dixon line. Its chief 

 enemy, a mite that is microscopical in size, 

 then seems to have arrived from Europe 

 on nursery stock and the pest no longer 

 threatened the entire orchard industry. In 

 places the Scale disappeared entirely and* 

 its appearance and disappearance has gone 

 on in irregular cycles down to our day. 



In studying the insect in Canada, a pe- 

 culiar condition was found in British Co- 

 lumbia. The scale insect arrived there on 



Apanteles lacteicolor. — Cocoons of this im- 

 portant enemy of the Brown Tail and Gipsy 

 Moths being picked from a rearing tray for 

 liberation in Eastern Canada. 



In Studying the Forest Tent insect a 

 curious situation was found in Alberta. In 

 the Sylvan Lake district there was an out- 

 break of the insect, destroying a good deal 

 of the Trembling Poplar, used locally for 

 building log barns and houses, and for the 

 ordinary needs of homesteading. None of 

 the insect parasites that attack this pest 

 Avere present, as the moths had evidently 



