Oak Apples

2016 July 13

We found these on an oak tree when we visited Lake of the Clouds on June 14, 2015. They are almost perfectly spherical, and around two inches in diameter.


They look like a fruit of some sort, but they aren’t. The fruit of an oak tree is an acorn, which looks nothing like these.


No, these are actually oak apple galls, which are formed on the oak trees by gall wasps. The wasps lay their eggs in leaf buds, and when the larvae hatch they produce chemicals that really mess up the growth of the leaf, making it into this porous spherical thing instead of a proper leaf. The local species is a single grub in there, living off of juices from the tree.

I posted one of these about six years ago that was found in the fall, and had turned brown. The insides end up looking like this:


We did keep one of the green ones, but nothing ever came out of it. I think it was picked too early. With any luck, one of these days we’ll find one on an oak tree on our property, and I’ll be able to keep an eye on it to let it mature properly, and then get pictures of whatever emerges.

4 Responses
  1. July 14, 2016

    By picked too early, you mean that whatever was inside starved as the flow of juices stopped? I’m a little surprised that the creature couldn’t just munch on the decaying plant materials all around it.

    Hmm. This just goes to show that my mom was right after all – if you’re a fussy eater, you may starve to death.

  2. July 14, 2016

    Yes. A lot of insects are excessively specific in their diets, which is why some are almost impossible to raise up in captivity.

  3. July 15, 2016

    I would bet that a more omnivorous gut is hard to support in a tiny organism.

  4. July 15, 2016

    I agree. In fact, it seems to me that the most omnivorous insects also tend to be either highly elongated, or have broader abdomens. Both of which would give more room for a longer gut.

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