Q: I have a dozen fothergilla bushes. I just noticed that one of them has strange cone-like shapes growing out of the leaves! None of the others have anything like this. What in the world is this?
A: Fothergilla (witch elder) is a member of the same family as witch hazel (^Hamamelis^) and winter hazel (^Corylopsis^). All are afflicted by witch hazel gall aphid. This tiny insect causes the tissue of a fothergilla leaf to swell into a cone around her.
Baby aphids are protected inside the gall until late summer, when they emerge to lay eggs on nearby shrubs. The galls don’t harm their host. With the time you save not worrying about them, read this fascinating research on the aphid: “Biting the Plant that Feeds You”.