Gall wasps

New species of gall wasp for DC?

That’s a Robin’s Pincushion gall (also called Bedeguar gall).

Key features visible in your photo:

• Clustered, lumpy structure rather than a single round ball.

• Woolly, fibrous surface (especially when fresher; yours looks dried out and weathered).

• Small exit holes — these are from the gall wasps or their parasites emerging.

About it:

• Cause: Formed by the gall wasp Diplolepis rosae.

• Host plant: Always on wild roses (Rosa species).

• Inside: The wasp larvae develop in chambers within the gall, safe from predators until they emerge.

• Name origin: The shaggy, red or pinkish appearance in summer looks like a “pincushion” of threads.

When fresh (summer/early autumn), the gall is greenish-pink to crimson and feathery. By winter, it dries, turns brown or greyish like in your photo, and often stays on the plant for many months.

Diplolepsis rosae - wikipedia