It was like something out of a fairytale. Hundreds of tiny orange butterflies rose up in waves before me as I walked down the grassy path. Each fluttered delicately for a moment before sinking back to rest on the green blades, the lupine leaves, and almost every surface in the community garden.

Their name, however, gives them away as an interloper. European skippers are native to many places—Europe, Scandinavia, North Africa, and Central Asia—but they aren’t native here.