60 PEAR. [1900 



niagnified figure of tlie "Pear Blister Mite," given at p. 59, and iu 

 those of the " Black Currant Gall Mite," given at pp. 43 and 45, 

 preceding) nt the fore part of the body. They propagate by eggs, but, 

 whether in egg or mite condition, are too small to be made out 

 without the help of a magnifier. 



The presence of the infestation, however, may be surely known of 

 by the various colours and other characteristics of the infested leaves, 

 as to some degree shown in the figure of the Pear leaf (natural size) 

 accompanying that of the Leaf-blister Mite. 



The history of the mites, as given by various observers, is that they 

 pass the winter in embryo, as well as in fully developed state, in the 

 leaf and flower-buds of one-year-old shoots, "embedded in the layer 

 of hair or downy felt inside the outer bud-scales," and as many as 

 seventeen specimens are recorded as having been found together. 

 From these scales the mites come out early in the spring, and attack 

 the young unfolding leaves. It has been considered that the mites 

 commence their infestation on the lowest leaves of the twigs, leaving 

 the upper leaves free at first ; and therefore that clearing the lower 

 leaves from the shoots where attack is seen to be taking possession 

 would have a good effect in checking progress of the mischief. 



The disease shows itself in the form of little blister-like spots, 

 somewhat raised "« each side of the leaf, but to which access is given 

 by a small central hole on the lower side of the leaf. The eggs are 

 laid within these blisters, and the central hole serves as a means of 

 passage to the mites, which spread themselves at their pleasure, and 

 very possibly carry on their attacks throughout the summer, until a 

 large part of the leaves are seriously injured for all serviceable 

 purposes. 



The little blisters at first may be red, or they may be red on one 

 side of the leaf and green on the other. With advance of age the 

 blisters become spongy in texture, and brownish or blackish in colour, 

 and before the leaves fall the mites leave the galls (blisters), and 

 secrete themselves amongst the scales of the winter buds (as before 

 mentioned) for the winter season. 



The above characteristics are quite sufficient guide for identification 

 of the nature of the attack. If anything more is required to distin- 

 guish it with certainty from the discoloured patches sometimes found 

 on Pear leaves, and known by the name of " Pear Scab," it is enough 

 to notice that in the mite-gall attacks there is a swelling of the blister 

 on both sidts of the leaf, with a central hole below ; and if a section is 

 cut through the blister, the diseased tissue will be found to form some- 

 thing of a cavity between the two sides of the leaf, within which (with 

 the help of a magnifier) the minute, cylindrical mites, in different 

 stages, and their eggs will very likely be found. 



