Biologist Larry Zettler was knee-deep in the cypress swamp’s dark, tannin-stained water when he spotted the clamshell orchid. Hanging from a mossy branch seven feet above the surface, the oxblood purple of the flower’s spiraling blossoms punctuated the grays and greens of the Everglades.
But as Zettler waded closer, something else stood out: fuzzy, white blotches enveloping the plant’s slender leaves. “It took my attention away from the beauty of the flower,” he says, “to something more sinister.”
Noting the orchid species and the GPS coordinates, Zettler unsheathed his scalpel, cut a one-centimeter square from the leaf, and slipped the sample into a vial. A phone call from the University of Florida’s insect lab two weeks later confirmed his suspicions -- the orchid was infested with boisduval scale, tiny invasive insects that have found their way into Florida's wet wildernesses, with fatal consequences for the state's most precious petals.
About 50 species, representing a quarter of the orchids found in North America, bloom in the cypress swamps of southwestern Florida. “It’s the gold mine of orchid diversity on the continent,” says Zettler. Sharing the same habitat as the state’s most famous albeit elusive endangered cat, these delicate plants grow in the Florida Panther National Wildlife Refuge as well as the Big Cypress and Fakahatchee Strand preserves. Many species inhabit only southern Florida and a few Caribbean islands, with the exact locations of the rarest orchids remaining closely guarded secrets. Poachers occasionally hack the blooms from their branches to sell them on the black market.
Already beleaguered by flower snatchers and threatened by habitat destruction and climate change, Florida’s wild orchids now face the dreaded boisduval scale. “Scale is one more thing that I have to watch out for,” says Larry Richardson, a biologist at the refuge. “It’s just one more thing that could pull down the overall health of the orchid population.”
Considered a scourge among orchid growers, boisduval hails from the American tropics. The tiny insect likely arrived in Florida among imported orchids and then traveled to the wilderness on hurricane winds.
In 2010, Zettler discovered that the bugs had penetrated deep into the swamps. During a separate research project, he had come across a ghost orchid crawling with some strange ants, which prompted a thorough flower survey within the Panther Refuge. This is when Zettler found the ailing clamshell and six other orchid species infected with three types of invasive scale. Boisduval being the worst of them all.
Once this scale finds an orchid, it stays put. “When you look at it with the naked eye, all you see is these white smudges,” says Zettler. These cotton-like, seemingly innocuous spots are hungry, parasitic colonies. The bugs’ protective, turtle-like shells cover their bodies as they clamp into an orchid’s stem or leaves to leach off the plant’s vital fluids.
With its lethal grip on Florida's floral diversity, boisduval threatens to undo much of Zettler's painstaking work. When he’s not wading through southern wetlands, the botanist is in the Midwest, where he directs the Orchid Recovery Program at Illinois College. There he breeds endangered orchids with the help of various fungi. “If you are an orchid, the fungus is like a pizza or spaghetti or a Danish,” he says. Deciphering which kinds of fungal food each orchid prefers isn’t easy, but once the seedlings grow big enough, Zettler heads south with them to bolster the cypress swamps' native flora. “Sometimes these orchids take years to grow in my lab,” he says, “and when I put them back in the wild, I don’t want them to get sick and die.”
Refuge managers are trying to prevent widespread harm by spot-treating infected flowers with insecticidal soap or a natural pesticide called neem oil. “There is some hope that we can control it, but it’s going to take more time, money, and vigilance,” says Richardson.
There's also the risk of reinfection -- especially since the flower’s host trees could remain infested with the insects. “Now that scale is in the most sensitive habitats on the continent, eradication will not be possible,” says Zettler.
As refuge managers brace for the ecological onslaught, the bug's biggest advantage may be its size. “Everyone is talking about massive pythons moving into the Everglades, and I’m not trying to belittle that,” says Zettler. “But invasive species are just as bad on the small scale.”