Walnut Gall

The walnut gall mite is an eriophyid mite. As an arachnid, this pest is more closely related to spiders and ticks than insects. Feeding on the plant's cellular contents irritates the plant tissue, causing the blisters. Mites reproduce rapidly, with females sometimes laying up to 80 eggs per month. Adults only live for about a month and several generations occur each year. Hot, dusty conditions encourage a rapid population increase. The mite overwinters in twigs and buds on the dormant walnut tree.