One of the things we make a big deal about with kids on school trips on the refuge is oak galls. We have an oak savannah with young trees and lots of the ping pong ball-sized galls. We tell them about how the female wasps lay their eggs in the oak bark and the tree makes these spheres that protect the eggs and larvae. It doesn’t even hurt the tree.  And…for centuries the tannic acid from the galls was combined with iron sulfate to make black ink called iron gall ink. Many of the great documents of history including the Declaration of Independence were written in oak gall ink. The teachers love that; science and history with one swipe.

So I just had to post this brief video I found from Deep Look, a new science program from KQED, San Francisco’s PBS station. I learned a lot from it. For instance, there are many kinds of galls, often on the same tree. The wasps that parasitize the tree often become host to parasitic young of other wasps. Amazing!

I’ve got a whole new kit of stories about the galls from this one little video. And I’m excited to go out and see if I can find different galls on the refuge oak trees!



  1. David – Thank you! A wonderful little vid .. and, more importantly, a very interesting new program from KQED. Another thing I learned about galls, incidentally, is how one of the things the wasp does is to inject a chemical/enzyme into the tree that mimics auxin, which is a chemical in most plants that serve to turn on/off growth. This leads directly to the growth of the gall.

    Ain’t nature kewl ..:-)) cu ~roland

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