Meet the Brazilian Velvet Ant, a Rare ‘Ultra-Black’ Wasp That’s So Dark It Absorbs Almost All Visible Light

The Caatinga is a stark, dry shrubland in northeastern Brazil. In Tupi, an Indigenous language, its name means “white forest,” describing the arid grasses, thorny trees and pale, stony soil that dominate the landscape.

But scurrying across this land of extreme whiteness is, paradoxically, one of the darkest animals on Earth: a species of velvet ant known as Traumatomutilla bifurca.

With its furry exterior and distinct black and white markings, the insect “looks like magic,” Vinicius Lopez, an entomologist at the Federal University of Triângulo Mineiro in Brazil, tells Katrina Miller of the New York Times.

As it happens, velvet ants, known colloquially to Brazilians as “sorcerer ants,” are actually a type of wasp, but the females, which are wingless, give the creatures their name. And, according to a study led by Lopez and published earlier this month in the Beilstein Journal of Nanotechnology, velvet ants have another claim to fame: The black parts of females possess a rare coloration known as “ultra-black,” so dark that it absorbs nearly all visible light.

“We have never seen this kind of color in the dragonflies or bees or beetles we have analyzed,” Rhainer Guillermo-Ferreira, another entomologist at the Federal University of Triângulo Mineiro who collaborated with Lopez on the paper, explains to the New York Times.

Unlike melanin, which makes animals like crows and black panthers appear dark, the researchers note that ultra-black is not just a matter of pigmentation. Instead, they write in the paper, these colors “are formed in nature by a sophisticated arrangement of microstructures” alongside dark pigments.

In the female velvet ant, these microstructures include overlapping stacks of lamellae, or layers of tissue, beneath dense, hair-like setae. Combined with a black pigment, these features in the insect’s exoskeleton “minimize reflectance and enhance light absorption,” the researchers write. Visible and ultraviolet light gets trapped in the layers, and less than 1 percent is able to escape.

Dakota McCoy, an evolutionary biologist at the University of Chicago who was not involved in the study, lauds the researchers’ use of multiple electron microscopy techniques “to try to see what the whole story was,” according to the New York Times.

This type of research is cutting-edge, because ultra-black coloration is extremely rare in the animal kingdom. Traumatomutilla bifurca is the first known ultra-black member of the Hymenoptera order, which includes more than 150,000 species of ants, wasps, sawflies and bees. Along with some butterflies, it is one of the only ultra-black insects.

Though this trait is rare, the advantages for animals that do possess it are wide-ranging. For peacock spiders and birds of paradise, the profound darkness may accentuate their vivid other colors and help them stand out to potential mates, according to a 2019 study. For deep-sea fish like the fangtooth, ultra-black serves as an “evolutionary tactic that gives some fishes an invisibility cloak,” Courtney Sexton wrote for Smithsonian magazine in 2020. And for vipers, a 2013 study suggests the intense coloration can help the snakes regulate their temperature.

In the case of female velvet ants, the little available evidence on their species’ mating preferences suggests the ultra-black hue doesn’t have to do with attracting males. And while it might play a role in protecting the wasps from ultraviolet light, the team couldn’t prove that.

Instead, the researchers propose that the wasps’ ultra-black is related to protection from predators. Velvet ants are already known as “indestructible insects” because of their painful stings, venom and hard exoskeletons, according to the paper. Their dark color could serve as a warning to would-be predators.

Some researchers see these natural advantages of ultra-black in animals as a blueprint for man-made materials. Ultra-black butterfly wings, for instance, hint at the possibility of extremely lightweight and absorptive material that could be used to harness solar energy, hone precision telescopes to detect the faintest light traveling across space or produce a camouflage coating for military vessels.

“The blackest black should be a constantly improving number,” Brian Wardle, a professor of aeronautics and astronautics at MIT, told Natalie Angier of the New York Times in 2019.

What makes ultra-black butterflies so black?

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Scientists are also on the hunt for the counterpart of ultra-black: ultra-white, a color that reflects up to 97.9 percent of sunlight. As climate change elevates temperatures across the globe, engineered ultra-white paint could help cool airplanes, cars and spacecraft without relying on air conditioning.

Still, many questions remain for researchers about how and why these extreme patterns of coloration occur in the wild. For instance, why do male velvet ants not have ultra-black pigmentation and instead reflect light at a much higher rate than females? What environmental pressures are responsible for dividing velvet ant evolution along these lines?

But, as Guillermo-Ferreira points out to the New York Times, these waspy denizens of the Caatinga are rich with research potential. “Every time we study velvet ants, they give us some new, interesting result.”

Eli Wizevich | | READ MORE

Eli Wizevich is a history correspondent for Smithsonian. He studied history at the University of Chicago and previously wrote for the El Paso Times.