This little beauty is an oak gall – the starter home of a baby wasp. It is a perfect delicate papery sphere in oak leaf brown. It is also a key ingredient in making historical ink.

The adult gall wasp lays her egg in a newly forming leaf. The oak responds by containing the damage in a gall. A win for the wasp, who has just coerced the oak tree into building a home for her baby. Clever girl.

There are many kinds of galls, signs of a plant reacting to the life around it – insects, fungi, bacteria. Begin spotting and sleuthing galls, and you’ll unlock secret stories of tiny and complicated lives, hiding in plain sight.

"Galls rarely cause significant damage to the host plant".

Keep your eyes sharp, and you can spot these vacant tiny homes on the forest floor. Either still attached to leaves, or blown free. This has been a particularly good year for finding oak galls in our woods. The gall above is a pretty perfect one. Still whole, and with the exit hole visible – made when the baby wasp left home.

Oak galls are not only great creches for little wasps, they are also a key ingredient in DIY ink. Mixing together oak galls, iron, water and oxygen results in a black ink that is not water soluble (though somewhat corrosive – don’t fill your fancy fountain pen with it). It took me a few years to forage enough galls to make a batch, but each gall was like finding treasure. My DIY tip: for an easy source of iron, try a few strands of steel wool.

Foraging for oak galls is exactly my kind of foraging. The gall’s work in the woods is over. I am not yanking blindly at the threads of the forest, or thundering into the woods to plunder. The insect has grown up and moved on. The first cycle is complete, and I can be part of it beginning a new one.

Happy Friday folks! 🖤🌱

For more information on oak gall ink, check out irongallink.org – a comprehensive website on oak gall ink maintained thanks to the Cultural Heritage Agency of the Netherlands.

For more information on galls, I highly recommend “Tracks & Signs of Insects” (Eiseman). One of the best books for making visible all the little worlds inside ours.