— io6 — 



Appeararice of the Mite. — As already stated the mite that causes 

 the Pear-leaf Blister is well known in Europe from whence it has 

 doubtless been imported on nursery stock. It is an exceedingly 

 small creature, being practically invisible to the unaided eye ; and 

 even with a good hand lens it appears merely as a minute white 

 speck. In fact, the best of microscopes is necessary in order to 

 study its structure satisfactorily. The entire length of the body 

 is about one one-hundred-and-fiftieth of an inch ; and the width 

 about one-fourth as great. The body is cylindrical in form, taper- 

 ing slightly towards each end. (Fig. 4.) It is ringed through- 

 out the greater part of its length with very fine rings. Sorauer 

 states that from 50 to 80 of these rings can be counted ; but we 

 find the number much greater. Fig. 4 was engraved from a pho- 

 tograph, and represents 

 quite accurately the rings 

 of the specimen studied. 

 As with other members of 

 the family to which this 

 mite belongs, there are 



only four legs. These are 

 Fig. A.-Phytoptus pyri. Adult mite. placed near the head end 



of the body, so that when the animal walks it drags its body 

 after it. The head is in the form of a conical snout, within which 

 are two sword-like jaws. The body and legs are furnished with a 

 few hairs which are constant in number and position ; these are 

 represented in the figure. 



Life Histoiy of the Species. — The eggs are laid hy the females 

 within the galls that they have formed, and here the young are 

 hatched. How long the young remain within the gall of their 

 parent has not been ascertained ; but sooner or later they escape 

 through the opening in it, and seeking a healthy part of the leaf 

 work their way into the tissue, thus starting a irew gall. By this 

 spreading of the young from the galls in which they have hatched 

 and starting new ones, the number of galls on a tree may become 

 rapidly multiplied. The mites live within the galls till the drying 

 of the leaves in the autumn ; then they migrate to the leaf buds 

 at the ends of the twigs ; where after working their way beneath 

 the leafy scales they remain throughout the winter. 



The mites instinctively make this migration as soon as the 

 leaves become dry. We found that whenever branches were 



