What are These Strange Orbs on My Oak Trees?

All from a shiny reddish ball. Or a fuzzy white ball. Or a corky brown ball. I’m talking oak galls, which commonly strike terror into the hearts of live oak tree owners this time of year. They are all caused by various species of small, stingless, solitary wasps. These wasps insert an egg (or several) into the tissue of small oak branches or young leaves, and are thought to modify the DNA of the plant, forcing the plant to produce a growth (the gall) that supplies both housing and food to the wasp larvae living inside. The saliva of the wasp applied at the time of the egg laying is thought to contain a virus that produces the genetic changes, so wasp larvae have been eating GMO’s for millions of years.

So wasps are defacing and eating your oak tree this fall, what you gonna do about it? As one writer says, “I recommend a cold drink, a good book and a comfortable chair.” ‘Cuz there’s nothing you can do or should do about it. Oak galls come in periodic waves, a few one year, more the next, and none the year after. Or close thereabouts. This is thought to be due variously to the tree buildup up of tannins to discourage the gall formers, and to a buildup of parasitic wasps (also stingless) that drill into the galls and lay their eggs on the gall inhabitant. Wild Mother Nature, there are even wasps that lay their eggs on wasp larvae that are consuming the original gall wasp larvae (did I put one too many eaters of larvae in there, I must proofread). The galls do not do substantial damage to your trees, and there’s really no way to get involved in the crazy gladiator’s pit of nature without screwing things up, SO DON’T SPRAY, just sit back in awe (or take a nap). And empty oak galls actually take in desirable boarders such as lacewing larvae and small spiders, scavenger ants and more beneficial wasps, all feeding on caterpillars and aphids.

Other fascinating factoids:

Oak galls were an important source of dark and permanent ink used for writing for over 12 centuries, and iron gall ink is still used by artists today. Did you know that a pen knife (aka a folding pocket knife) was constructed to make quill pens from feathers, and to periodically shape a new point on the quill as it wears? You cannot use the medieval oak gall recipe for black ink with a metal tip pen because it is too corrosive to metals.

Oak galls have recognized medicinal uses due to the high tannin content (and also used for tanning).

Before his landmark work on human sexuality, Alfred Kinsey was known for his study of gall wasps.

– James