Host and distribution. This species occurs world wide in all pear growing areas.

Relation to host. Causing blisters or galls on lower surfaces of leaves. Galls first appear as minute green pimples with a reddish tinge, but later become red.

Host and distribution. This species has a world wide distribution. It occurs in all pear growing areas of South Africa and has been recorded from Egypt and Zimbabwe.

Relation to host. The most familiar symptom caused by these mites is blisters or galls on the un- dersurfaces of leaves. The galls first appear as minute greenish pimples with a reddish tinge but as their size increases the galls become red and often form brilliantly coloured spots on the leaves. Since the early 1920's it has been known that there is also a race of E. pyri that causes extensive damage to fruit buds and an abnormal drop of blossoms and immature fruit but does not produce leaf galls.

[B]listers [first] appear as reddish or pinkish swellings, later as rough red swellings on the lower surface of the leaf blade. Often they coalesce, covering a large area of the leaf blade alongside the midrib.
As blisters become infested with mites, they turn dark brown to black, and by the end of the growing season the affected tissue has become dead and shrunken. Blisters ... not colonized by mites are pale green ... [B]listers without exit holes never contain mites.