What is the cotton ball with pink spots on my oak?

A wool sower gall made by a tiny wasp.

Will it hurt my tree?

No; the galls typically do not harm the tree.

On this page

Galls are fluffy and white at first, then white with pink spots, then brownish.^[1][2]
Inside are small, hard, tan seed-like structures, each holding a grub; the gall is also called the oak seed gall.^[1][2]
Adults are about 1/8 inch long, dark brown, with a flattened abdomen.^[1][2]

Look-alike	How to tell them apart
Oak gall wasps	Many other gall wasps make galls on oaks; the wool sower gall is specific to white oaks in spring.^[1]

Found where white oaks grow, including North Carolina and South Carolina.^[1][2]

Gall wasps alternate generations; this generation develops in stem tissue, and adults tunnel out and usually emerge in June or July.^[1][2]

The female lays eggs in young leaf or stem tissue, and the tree forms the gall in response to the larva's secretions.^[2]

White oak is the main host; chestnut oak and swamp white oak are also listed.^[1]
The galls typically do not harm the tree.^[2]

None to people or pets.^[1][2]

By the time galls are noticed, control is too late; the grubs are protected inside the gall, and the galls are harmless.^[1][2]

What is the cotton ball with pink spots on my oak?: A wool sower gall made by a tiny wasp.^[1][2]
Will it hurt my tree?: No; the galls typically do not harm the tree.^[2]

NC State Extension, “Wool Sower Gall Wasp (PDIC Factsheet).” content.ces.ncsu.edu/wool-sower-gall-wasp (accessed 2026-10-16)
Clemson Cooperative Extension Home & Garden Information Center, “Wool Sower Gall (Callirhytis seminator): Causes, Life Cycle and Control.” hgic.clemson.edu/wool-sower-gall-callirhytis-seminator-causes-life-cycle-control/ (accessed 2026-10-16)
iNaturalist, “Callirhytis seminator taxon page (order and family).” www.inaturalist.org/taxa/123900 (accessed 2026-10-06)

Updated 2026-10-17. Built from sourced records. Spot an error? Tell us.