Galls are abnormal plant growths that can be caused by insects, fungi, bacteria, nematode worms and mites. Insects cause the greatest number of galls and induce the greatest variety of structures. Galls provide both food and shelter for the organisms living within them. Galls develop during the growing season, often in buds and on leaves. Pine Cone Willow Galls, named for their resemblance to small pine cones, are found on willows, typically in terminal buds. A gall midge (Rhabdophaga strobiloides) is responsible for the willow bud going haywire and developing abnormally. (No-one has determined exactly how insects cause galls, whether it’s the act of laying eggs in or on the plant, or if it’s somehow connected to the chewing of the larvae into the plant.) Each gall-making insect has a specific host plant, or small group of related plant. The galls that each insect species induces and lives in while developing into an adult has a recognizable shape and size. When you think you’re seeing pines cones on willow trees, you’re not hallucinating, you’ve just discovered the temporary home and food supply of a tiny fly, known as a midge.
In March and April, beavers consume a lot of tree bark, but come summer, approximately 90 % of a beaver’s diet consists of grasses, aquatic plants, and other herbaceous vegetation. Of the woody plants that they do eat during the warmer months, aspen/poplar (in photograph) and willow are favorites. It appears that beavers use their sense of smell in order to find their tree of choice. The greater the distance from the pond, the more selective beavers are in terms of species chosen – they go as far as a tenth of a mile away and up steep slopes for aspen!