Finally: The Mystery ‘Golf Balls’ Found In New York Explained

Growing up in the Hudson Valley, I spent much of my free time exploring the forest around my house in Ulster County, NY. While my walks in the woods led me to find artifacts ranging from shotgun shells to a literal piano (I took home all the keys and hung them on my bedroom wall), there was always a natural phenomenon that caught my attention: golf balls.

If you've spent any time in the New York wilderness, you know exactly what I'm talking about. These small, round balls look exactly like something Tiger Woods would take on tour, but instead of being made by Callaway or Titleist, they're created by nature. But what are they?

Mystery "Golf Balls" in New York State

As kids, we called them smoke bombs, based on the fact that they were fragile and seemed to emit a cloud of, well, something, when crushed. As an adult, I finally have my answer... and it was nothing I ever expected.

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Oak Apple Galls in New York State

If you come across one of these "golf balls" in the wild, you're most likely looking at an Oak Apple Gall. While they are naturally occurring in many New York woods, it's not the trees that create the balls, but rather one special insect. How it happens is fascinating.

What are Plant Galls?

Plant galls in general are caused when some sort of animal lays an egg in a leaf or stem. While some galls turn into wild shapes ranging from lumps to actual spikes (above), galls caused by the oak apple gall wasp look like brown golf balls, Naturalist Matt Pelligrine explains how they get their shape:

The galls are the work of the Spongy Oak Apple Wasp, a tiny parasitic wasp that stings oak leaf buds in the spring.  Once stung, the leaf forms a gall around the wasp’s egg.  The gall provides both food and a hiding place for the young wasp grub.

As far as I'm concerned, the fact that a small insect can turn an oak leaf into a "golf ball" is natural magic. It's also wild to know that if you come across one of these galls still attached to a leaf, there's most likely a little grub inside biding its time before it transforms into a wasp and is released into the world.

One of the best parts of living in the Hudson Valley is discovering all the wild things nature has to offer. From golf balls made by wasps to carnivorous plants, there's something to intrigue even the most jaded New Yorker. Check out which plants and animals are actually dangerous for our local ecosystem below.