Of all the gall

by Caroline Brown

On a walk this past weekend, I saw some oak galls. Sometimes called oak apples or oak potatoes, oak galls are abnormal growths on oak leaves, twigs, or stems that are made from the plant tissue itself by parasitic wasps.

Galls can be made by fungi, bacteria, mites, or other insects. And they appear on other plants besides oaks. The gall-making insect produces growth-regulating chemicals that cause the plant tissue to grow unnaturally and abnormally. The insect takes advantage of plant tissue that is growing at a very fast rate in the spring, producing the growth chemicals that cause the plant tissue to form the gall.

Insects that form galls are either larvae that have already been laid on the plant, or an adult insect that has recently laid eggs. The larvae develop inside the gall, feeding first on the host plant’s nutrients until the gall is fully developed, and later on the tissue of gall itself.

Most gall wasps spend at least 2 years in the gall before reaching maturity and leaving the gall. Adult wasps usually overwinter in trees near the host plant. Gall wasps are in the family (Cynipidae). I’m not sure exactly which type of gall wasp made this gall.

In general, galls are harmless, although sometimes they can cause premature leaf drop or halt photosynthesis (the plant’s food-making process). Most homeowners think they’re ugly, though, and worry about damage to their plants. But chemicals or pesticides are rarely suggested to control galls–the risk isn’t worth the return.

After all, it’s just “nay-cha,” as they say here in Little Rhody.


7 Comments to “Of all the gall”

  1. Well, “nay-cha,” as you say, has to take her course. πŸ™‚ I have to admit, I don’t find them very attractive either, but I’m sure they’re necessary and that wasps are here for a reason, too.

  2. I think they look great – totally funky! Sort of like miniature burls. πŸ™‚ Are they solid, or more papery?

  3. They’re kinda cool looking in a way….like natural Christmas ornaments. They’re solid…kinda like nuts, but not as heavy. On Garden Rant, they featured an artist who made sculptures of them! He had to finish the sculpture outside when all the wasps hatched in his house.

  4. Great minds think alike, that’s the first thing I thought of, Christmas ornaments! LOL

  5. I myself think the wasp galls are interesting, although I do know that it is not healthy for the tree itself, where I live (California) in my part of the town most of us here are all orgainic city gardners and one of the neighbors near by has a California Oak tree growing in her back yard that she said has been there for years, she said she has never spray the tree to kill the wasps for she knows that wasps are good for something.

    If you never done it before, take a Wasp ball that has fallen off of a plant and cut the ball open, it is insteresting to see all of the small little tunnels in the ball itself.

  6. Oh one more thing on gall balls, make sure the fallen ball is very dry and feels very light before cutting into it.

  7. These things look trippy… awesome pictures.

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