64 



THE PEAR LEAF BLISTER MITE. 



(Eriophyes pyri, Nalepa.) 



The Pear Leal 'Blister Mite is a troublesome pest of the 

 pear tree and may do much damage, though the injury it 

 causes often seems to pass unrecognised. This is regrettable 

 since, as in the case of most pests, an attack in its early stage 

 is far easier to deal with than later when the infestation >s 

 bad. 



The Pear Leaf Blister Mite occurs everywhere, but judging 

 by the records would seem to be more troublesome in the 

 southern half of the country than in the northern. The mite 

 is also a pest on the Continent of Europe and in America. 



Plants Attacked and Nature of Damage. The chief 

 damage is done to pear, but the apple is also occasionally 

 attacked, while among wild and garden plants, Mountain Ash 

 or Eowan, White Beam, Wild Service Tree and Cotoneaster 

 all suffer at times from the Mite. 



The nature of the damage is much the same in each case, 

 but the following description refers to pear. When the leaves 

 (Fig. 2) of an infested tree have expanded in spring it wlil be 

 noticed that the upper surface of an attacked leaf is dotted 

 with small yellowish- green pimples, the underside showing 

 corresponding impressions. These pimples or blisters are 

 usually more numerous on the half of the leaf on each side of 

 the midrib than towards the margins. In some cases the 

 blisters, while starting green in colour, scon turn pink or red. 

 Later the blisters become brownish, and the whole leaf often 

 turns black and dies in the latter half of summer. In the 

 cose of, trees badly infested the young fruitlets and their stalks 

 are also attacked, causing either malformation of the fruit 

 or more usually its death, and fall from the tree when 

 quite young. 



Description of Pest and Life-History. The damage is 

 caused by a very minute mite so small (less than 1/100 inch) 

 as to be invisible without the aid of a microscope. The 

 general appearance of the mite is shown by Fig. 1, and further 

 description is unnecessary as the pest will be identified^ by 

 the damage it causes and not by its structural characteristics. 



The mites spend the winter under the outer bud-scales of 

 the buds. In spring they pass on to the leaves and burrow 

 into the under-surface, setting up the irritation which results 

 in the blister-like pimples on the leaves. In these^ blisters 

 tbe female mites lay eggs and the young feed within for a 

 period and then pass out through a minute hole on the 

 underside of the blister and burrow in at another spot, so 

 forming fresh blisters. Reproduction goes on throughout 

 the summer season, but before the leaf falls the mites move 

 again to the shelter of the young buds in which to spend 

 ihe winter. 



