On my road trip to Michigan, I visited Library Park in Elk Rapids. The Park is on the shores of Lake Michigan, with a beach, a harbor and a Jetty. At the end of the jetty were a few clumps of beach grass, bushes and a short willow. Such a harsh habitat does not teem with insect diversity, but an entomologist can intensively search the few available resources.
On the willow, I found a single gypsy moth caterpillar. How did it arrive? The willow was hundreds of meters from the nearest tree. Gypsy moth females are flightless and lay eggs in clusters. It is unlikely that a female gypsy moth laid a single egg on the bush. The egg could have been part of a mass laid on a piece of wood that drifted to the jetty.Possibly the caterpillar traveled by air. Gypsy moth larvae can spin down from trees on silken thread and catch a ride on the wind. If this happened, this single larva was lucky enough to land on the only possible plant that could support it before it was blown into the miles of the watery death of nearby Lake Michigan.