Oregon White Oaks are a host for many gall wasps. The fimbriate gall wasp forms a fuzzy, red structure that looks like a flower is trying to emerge out of the leaf—it kind of reminds me of a hairy rose hip. A dictionary defines fimbriate as “Botany, Zoology. having a border of hairs or filiform processes.” I think its name could be more descriptive to include words like flaming, blazing, flaring, crimson, furry, etc. August Jackson put together a guide called Oak Gall Wasps of Mount Pisgah. About fimbriate galls, he writes, “small galls in spring on midrib of leaf bases, producing spines. Starting red then fading to brown.” The guide is available on the arboretum’s website. Find it here.
The development of galls hasn’t been completely figured out. Galls are created when the wasp lays its egg in the developing plant tissue of the tree which can be on the leaves or branches. The egg interferes with normal plant growth and creates a gall that protects the egg and provides food for the developing larva. Each gall wasp creates a unique structure that is beautiful and interesting to explore.
I think I’ll call this one the Crimson Comet Gall.
