2. ANIMALS INJURIOUS TO FRUIT TREES. 



THE PEAR-LEAF BLISTER MITE. 



Eriophyes piri (Pagenst.), Nal. 



This pest has been on the increase for some years past, and is 

 still spreading- annually over a wider area. 



Unlike most species of Eriophyes, this one feeds upon a variety 

 of plants of the same Natural Order. Prof. Nalepa records it on Pear, 

 Apple, White Beam Tree (Pyrus aria), Wild Service Tree (Pyrus 

 terminaUs), Rowan (Pyrus aucuparia), and Cotoneaster vulgaris. 



The mite attacks both leaves and developing fruits. In the early 

 spring the mites leave their winter quarters, viz., beneath the scales 

 of the last year's buds, and gall the young leaves ; here the females 

 lay their eggs, and fresh broods arise, which spread over, usually, 

 the leaves of the terminal twigs and form fresh blisters. On the 

 first approach of autumn and before the leaves fall, the mites repair 

 to their winter quarters. Leaves examined in September and 

 October were quite free from mites, although I have found them 

 present as late as the end of September. 



PREVENTIVE AND REMEDIAL MEASURES. 



A number of experiments have been made with a view to testing 

 the value of spraying with (i) paraffin emulsion, and (2) a solution 

 of potassium sulphide. 



1. Paraffin Emulsion. The trees were sprayed three times in 

 the spring of 1909, but were quite as badly attacked in 1910 as 

 previously. 



2. Potassium Sulphide Solution. Two badly-attacked trees were 

 sprayed twice in the spring of 1910, and have materially benefited. 

 The first spraying was applied just as the trees were coming into 

 leaf, and the second about a fortnight later. Although in 1909 there 

 was scarcely a leaf that was not blistered, it was quite the exception 

 to find one during 1910. 



The value of sulphur is now so generally recognised as an 

 acaricide, that I fully expected that a solution of potassium sulphide 

 would be effective, and this has proved to be the case. 



