Wool Sower Galls

A woody Southern landscape in spring is full of surprises, for instance, delightful spring ephemerals like trilliums. You can also find interesting galls, if you’re into that sort of thing.

Galls are abnormal growths that appear on leaves, flowers, stems and roots of plants. They’re often caused by insects laying their eggs, causing unusual growths. The puffy white ball with brown spots pictured here is an oak sower gall, also called a wool sower gall due to its fuzzy appearance.

Wool Sower Gall

Wool sower galls are formed by wool sower wasp grubs. The puffy shape is made by the grubs’ secretions that form chambers for the grubs to develop. I like this factoid: wool sower grubs have alternate generations. One will be a leaf gall wasp, and the next will be a stem gall wasp. (Looks like a stem gall generation visited my garden.)

The galls appear in spring just as the trees are leafing out and they’re partial to white oak trees.

What’s important for your home landscape is that wool sower galls and wasps are part of your local ecosystem. They rarely become so prevalent that they harm trees. There’s no need to spray a chemical or even get out your pruning shears. They’ll complete their life cycles and move on.

The second thing you can do is to show a young person (or curious adult) how nature works in this instance. Show them how to identify the tree using a plant identification app or a field guide (I know, old school 😂) by observing the leaf shape and the bark. Take a few minutes to explain how the wasps need the trees to complete their life cycle.

You can also show your young person how to look up accurate science-based information on what you find in your yard. I looked up wool sower galls and searched for Cooperative Extension information. You can type “extension” or “site:edu” for the best results.

The source I used for this story is NC State Extension.

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