every season a leaf-cutter bee chews hundreds of holes in my redbud tree's leaves. The tree is only three years old and I worry that it won't thrive. How can I protect it?
Leaf cutter bees are mason bees! Sweet wonderful critical guys! DO NOT WORRY ABOUT THESE. I really don't think these could harm a baby much less a tree. Please send some pictures of what is happening. Bees are actually far more important than a tree (although cercis canadensis is a super wonderful tree). Go out at different times of the day to observe. Go at night in particular. Send pictures of damaged leaves, the insects you find, I'd like to see the base of the trunk and what is happening between soil and bark. Also, pruning these guys early is important, for their branching is one of their best attributes.
What are you using for fertilizer? Watering?