106 THE REPORT OF THE No. 36 



ordinary sprayings and giving an extra application about August let or as late as 

 safe before the fruit is ripe. It is clear, however, from the presence of the mites m 

 scale infested areas where strong limensulphur is used before the buds burst, that 

 this mixture will not destroy the eggs. 



Prof. Dearness : I should like to ask how the eggs of Bryohia pratensis can 

 be distinguished from these of this new species. 



Prof. Caesar : There does not seem to be any way of distinguishing them. 



Prof. Brittain : Has anybody noticed in Ontario or the Maritime Provinces 

 that so called rusty leaf or silver leaf mite ? It has occurred in British Columbia 

 causing this silvery appearance on the leaves to be mistaken for a disease called 

 Silver Leaf, When I left British Columbia, I took with me Northern Spy nursery 

 stock which had these incrustations. It makes very unsightly looking nursery stock. 

 This year the mites came out proving it to be the same species. It makes these 

 incrustations and spoils the appearance of the bark. It does not do any harm. 

 They do not seem to flourish in British Columbia, but they have found mites of the 

 same species in King's County, so they are apparently found there too. It is well 

 distrihuted in North America, in Washington, Oregon and New York State, so there 

 is nothing surprising about it. There is another mite in British Columbia which 

 makes its appearance on leaves. It causes raised blisters, black in colour or very dark. 

 The mites are on the under side hidden among the hairs and are never found much 

 unless you look with a microscope. I saw some leaves on apple trees -with marks 

 'which looked as if they might be there. Has anybody found that mite in Eastern 

 Canada ? I have seen botanists deceived by it more than once, thinking they had the 

 apple scab. In fact it has been diagnosed as apple scab frequently. 



The President : Mr. T, Jarvis is more of a specialist on these mites, but that 

 question as to the Phytoptid mite is very interesting. Prof. Crosby is probably 

 interested in the matter because he may have had similar experiences. Three years 

 ago Mr. Giissow, the Dominion Botanist, and I first received specimens of this 

 northern spy nursery stock from the Coldstream Nurseries in British Columbia 

 bearing these reddish hrown incrustations to which Prof. Brittain has referred. I 

 am not sure, but I think the stock at the time was being condemned as being diseased 

 and not fit for sale, and it was sent up to have the disease determined. I looked 

 into the matter personally and examined quite a number of these young seedlings, 

 and found the characteristic small tubercles which are caused by the Empoasca when 

 it deposits its eggs. I found the egg of this insect and naturally assumed that this 

 was the cause of the trouble. The next spring we reared the larvae of Empoasca mali 

 from the tubercles which later took the form of incrustations where the bark was 

 ruptured. At that time the silver leaf on the apples in British Columbia was at- 

 tracting attention. I do not know whether it was Prof. Brittain himself or in con- 

 junction with Mr. Giissow, who discovered that there were two kinds of silver leaf, 

 one caused by the Stereum and the otlier caused by the little Phytoptid mite which 

 I believe also causes silver leaf in peach, 1 think the original record from North 

 America was on peach. Later we had further samples sent of these seedlings bearing 

 incrustations. Mr, Dash of the Provincial Horticultural Department found these 

 Phytoptid mites under the brown incrustations which we said wero due to the 

 emergence of the Empoasca larvee. -We corresponded about the matter each -referring 

 to the same thing though believing the other meant something different. Finally 

 when we found that both of us had been talking about the same thing, the whole 

 story worked out in this way. The Empoasca deposits egg under the surface of the 

 bark which is ruptured when the larva emerges. This rupture increases in size with 



