Pearleaf blister mite

Eriophyes pyri


The pear leaf pox mite(Eriophyes pyri) is a gall mite found in pome fruit that covers much of the leaves with pox when heavily infested. This disrupts the tree's nutrition and shoot formation.


The pearleaf pox mite belongs to the tiny representatives of the gall mites (Eriophyidae) within the order of mites (Acari) among the arachnids (Araneae). The microscopic gall mites (only 0.2 mm long) are worm-shaped and have two pairs of legs and the mouthparts at the front end.


During spring shoots, gall mites migrate to the leaves (and fruits), where their sucking activity causes roundish-oval growths (poxes) on the leaf surfaces. In these poxes they lodge and lay their eggs. The next generation of gall mites also resides in these poxes and sucks in the plant tissue. When the leaves die, they leave the pox through a small opening and colonize new leaves. There are several generations annually. The gall mites of the last generation migrate to the buds and overwinter in groups between the bud scales.

Damage symptoms

In spring, pock-like formations can be seen on the upper and lower sides of the leaves, which are initially green and reddish, but soon turn blackish brown. Inside these pocks are the gall mites, which are not visible to the naked eye, but only with a magnifying glass or under a microscope.

Host plants

The preferred host plant is pear, less commonly apple, hawthorn(Crataegus spp.), and hackberry (Sorbus spp.).


The pearleaf pox mite occurs worldwide.

Propagation and transmission

Gall mites are spread passively by wind, insects and birds.

Economic importance

In case of heavy infestation, a large part of the leaves and leaf surfaces are covered with pox, which disrupts the tree's nutrition and thus the formation of shoots.

The pear leaf pox mite occurs frequently, especially in nurseries.

Prevention and control

In case of low infestation, removal of infested leaves before the gall mites migrate is sufficient. This prevents overwintering and reduces the initial population for the next year.

If necessary, targeted control is possible only at the time of budbreak, when the gall mites have left their winter quarters, before the first pox appear. Net sulfur preparations and acaricides suitable for controlling free-living gall mites can be used (see list of plant protection products approved in Austria).

Last updated: 31.10.2023

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