DESCRIPTION: These elongated pimple-like galls are always found in the angles of the midrib and main veins of the leaf and form an alternating line that is easily indentifiable. Strangely the galls never reach the tip of the leaf and more often than not cause curvature of the midrib. The galls range from pale green to deep red in colour and have a small hairy opening on the underside of the leaf with more russet coloured hairs on the inisde where many mites are located. When the gall matures the mites abandon the growth and take winter refuge in old cones and bark crevices. DISTRIBUTION: Locally common throughout from May to September. HABITAT: On Alder leaves.
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