Oak Galls: California Gall Wasps

“A green little world
With me at its heart!
A house grown by magic,
Of a green stem, a part.

My walls give me food
And protect me from foes,
I eat at my leisure,
In safety repose.

My house hath no window,
‘Tis dark as the night!
But I make me a door
And batten it tight.

And when my wings grow
I throw wide my door;
And to my green castle
I return nevermore.”

The above poem about galls is shared on page 338 of theHandbook of Nature Study.
We found this interesting object on our nature walk a few weeks ago. I knew it was called a gall but I wasn’t sure at all where it came from or what it was for. After doing some research intheHandbook of Nature Study, I now know a lot about these interesting little houses.

Here’s what it says on page 335:“There are many forms of these gall dwellings, and they may grow upon the root, branch, leaf, blossom, or fruit. The miraculous thing about them is that each kind of insect builds its magical house on a certain part of a certain species of tree or plant; and the house is always of a certain definite form on the outside and of a certain particular pattern within. Many widely differing species of insects are gall makers; and he who is skilled in gall lore knows, when he looks at the outside of the house, knows just what insect dwells within it.”

So now I know it is a home for an insect. I have grown up around these objects but have never taken the time to really get to know them. Here is some more on how they are formed.

From page 335-336“A little, four-winged, fly-like creature, a wasp, lays its eggs, early in the season, on the leaf of the scarlet oak. As soon as the larva hatches, it begins to eat into the substance of one of the leaf veins. As it eats, it discharges through its mouth into the tissues of the leaf a substance which is secreted from glands within its body. Immediately the building of the house commences; out around the little creature grow radiating vegetable fibers, showing by their position plainly that the grub is the center of all of this new growth; meanwhile, a smooth, thin covering completely encloses the globular house; larger and larger grows the house until we have what we are accustomed to call an oak apple, so large is it.”