What Gall!

Like cotton-candy splashed with raspberry juice, Woolly Catkin Gall Wasp/Callirhytis quercusoperator bunches up the flowers of a Northern Red Oak.

Meanwhile, on a Scarlet Oak, it’s mostly white.

These are created by tiny wasps that take control of the plant to induce this unique growth on the catkins. The wasp larvae grow up inside, eating the plant growth that also protects them. Somewhat protects them: all sorts of things want to get inside an oak gall, to eat the wasp, find shelter, and/or also feast on the plant.

This gall should not to be confused with Wool Sower Gall Wasp/Callirhytis seminator, which grows off the twigs. I have not seen that one in NYC, but I found some in Virginia in a small park near a plaque honoring early American botanist John Clayton.