Officials at the refuge put signs up in July to warn visitors about the flies and set traps out in the marsh to help control the population, but they remain the bane of the unprotected visitor. Opinion differs on whether conventional insect repellent is effective against greenheads, but popular lore has it that Avon's "Skin-so-soft" bath oil keeps them at bay.
Gette tries to remind himself that the flies are an important part of the marsh's ecosystem, providing abundant and nutritious food for many bird species. But even for a conscientious naturalist, it's hard to love the greenhead.
"They have a role to play, it's true," he said. "But it doesn't mean I have to like them."