Now that most of the leaves have fallen, it’s a good time to look for galls that form on woody plants. Willows are host to a great number of gall-making insects, including tiny flies called midges. The most common species of willow gall midge is the Willow Beaked-Gall Midge, Rabdophaga rididae. In the spring, after mating, the adult female midge lays an egg in a willow bud (often terminal) that is just starting to expand. The egg soon hatches and the larva burrows deeper into the bud, which causes the bud tissue to swell and form a gall, usually with a “beak” at the top. The larva remains inside the gall through the winter, where it has a constant supply of food (the interior of the gall) and shelter. In the spring the larva pupates, and an adult midge emerges and begins the cycle all over again. Some gall midges are crop pests, but willows are not significantly damaged by the Willow Beaked-Ball Midge.
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