I appreciate hearing from Ted MacRae regarding the origin of galls found on many plants at Bosque Santa Lucia. The attached image of galls on manioc leaves (Manihot esculenta) is one example I posted on this blog not long ago. To quote Ted, Many groups of insects (and non-insect arthropods) can cause galls - flies, wasps, and mites to name a few. That thoughtful comment tells me much more about galls than I ever knew before.
Ted's blog, link above, is entitled Experiences and Reflections of a Missouri Naturalist.