1908 ENTOMOLOGICAL SOCIETY. 15 



CONFERENCE ON THE CHIEF INSECT PESTS OF THE SEASON. 

 The Leaf Blister Mite. 



The Chairman, Mr. T. D. Jarvis, announced that the rest of the after- 

 noon would be devoted to a discussion of some of the chief insect pests of the 

 season, taking up especially those injurious to fruit culture. The first to 

 which he would draw the attention of the meeting was the Leaf Blister Mite 

 (Eriophyes pyri) which attacks the foliage of the pear and apple, and has 

 during late years slowly and steadily spread throughout Ontario. It is an 

 almost microscopical mite and by its attacks causes little blisters to appear 

 which become dark brown on the under side of the leaves. 



Mr. Caesae showed some mounted specimens of the Blister Mite and 

 stated that they are to be found on the under side of pear and apple leaves on 

 which they produce dark swellings which look like a fungus disease. In 

 travelling through the province this year he had found this Blister Mite in 

 the Niagara district, at St. Catharines, Grimsby and other places; also in 

 Essex county, some in Norfolk, a great deal in Prince Edward county, a 

 considerable amount in Peel county. In his own home orchard in Peel 

 county were some pear trees that had hardly a single leaf that was not 

 covered with the work of the Mite. A year ago here at the College he found 

 it in the orchard on the pears, but this year he could not find any. The only 

 explanation that he knew of for its disappearance in the orchard was that the 

 trees had been sprayed with lime-sulphur. It is found that this Blister Mite 

 winters over in the nearly full grown stage. It is such a tiny little animal 

 that it can hardly be seen with the naked eye. Before winter comes on it 

 gets under the scales of the buds where the lime-sulphur wash may reach 

 and destroy it. There is also another remedy that has given good results for 

 the destruction of this pest, viz. : kerosene emulsion. Mr. Caesar did not 

 know how injurious the pest might be, but from the diseased trees which 

 he had seen, it must do a great deal of damage by lessening the power of the 

 tree to supply food for its necessary growth. 



Mr. Jarvis : It is interesting to hear that the lime-sulphur wash may 

 destroy this pest. A species of this genus of mite with similar habits attacks 

 perhaps forty or fifty of our forest and shade trees, and if the lime-sulphur 

 will kill them, it will be a good remedy for the Soft Maple mite as well as 

 many others which winter in the leaf buds. 



Dr. Felt: The Blister Mite, in some parts of New York state has been 

 very injurious. I noticed one place in particular where some trees were so 

 badly infested by Blister Mites that one could see the brown foliage a quarter 

 of a mile away, and when the foliage is in that condition there is no doubt 

 that the trees are seriously injured. Our experiments go far to show that 

 lime-sulphur or an application of miscible oils or kerosene emulsion in early 

 spring is very effective in controlling the mites. 



Respecting the value of the lime-sulphur wash on Maple trees it would 

 depend on whether it would go under the bud scales and thus destroy the 

 mites; he was doubtful whether it would do so. 



Mr. Jarvis : I have had no experience with the lime-sulphur on these 

 trees; I only suggested its use, but as Dr. Felt implies the scales of the 

 Maple buds are very compact and perhaps the wash would not get into them 

 60 well as it would those that are looser. 



Mr. Caesar wished to know whether the wash had ever been applied in 

 the fall instead of the spring with the same good results. 



