This Fly Larva Turned Its Butt Into a Termite’s Head. The Big Question: What Will It Look Like as an Adult?

When people think of camouflage in nature, they imagine octopuses, cuttlefish, and chameleons blending into their surroundings. But other strategies exist, like butterflies with wing patterns that confuse birds or stick insects resembling twigs. One case stands out even more: A fly larva that has turned its butt into a termite’s head.

It works so well that the termites even feed it.

A lucky discovery. That seemingly adorable creature in the cover image? It’s actually the rear of a blue bottle fly larva. It has fake antennae and fake eyes—an impressive adaptation designed for one purpose: to deceive termites. The discovery happened by chance.

Researchers from the Institute of Evolutionary Biology (IBE), the Spanish National Research Council, and Pompeu Fabra University in Spain were studying butterflies and ants in Morocco’s Anti-Atlas mountains. When heavy rains grounded the butterflies, they turned their attention to ants. “When we lifted a stone we found a termite mound with three fly larvae that we had never seen before,” they explained in an IBE report.

A termite mask. The researchers called it a “chance finding.” After three more expeditions and hundreds of overturned stones, they found only two additional larvae—both in another termite mound. Their study, published in Current Biology, details the discovery of a larva with “a unique disguise.”

The blue bottle fly larva’s rear features a “termite mask”—a non-functional head with fake antennae, palps, and eyes resembling those of a large harvester termite. These “eyes” serve an unexpected function: They’re actually the larva’s breathing openings.

The perfect twin. Most termites live in deep, dark environments where eyes are unnecessary. But harvester termites, which collect grass on the surface, have functional eyes. The larva mimics them, using its spiracles to imitate termite eyes.

3D camouflage. These larvae are fascinating for two reasons. First, their false head isn’t just for show—it features extra antennae running along their bodies, resembling tentacles. Researchers believe this allows them to communicate with multiple termites at once. Since termite mounds are pitch black, any termite brushing against the larva’s “tentacle” assumes it’s one of their own.

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But the trick isn’t just about touch. Termites recognize each other by scent, using unique chemical signatures to identify members of their colony. The larva has adapted to this as well, mimicking the colony’s scent in what researchers call a “chemical disguise.”

They even feed it. “The larvae are not only tolerated, but they constantly communicate with the termites through contact with their antenna-like tentacles,” Roger Vila, one of the lead researchers, said. He suspects termites might even feed the larva through its functional head, though tests are still underway. One photo from the study shows what appears to be mouth-to-mouth feeding.

Accelerated evolution. Vila notes that flies often imitate other insects to engage in social parasitism. For instance, humpbacked flies also mimic termites—but as adults, not as larvae.

The common ancestor of these flies dates back more than 150 million years—far longer than the evolutionary gap between humans and mice. “We are therefore confident that we have discovered a new case of social integration evolution,” Vila stated. He believes the blue bottle larva evolved rapidly to develop this extreme adaptation.

A difficult mystery to solve. The researcher said that discoveries like this highlight how little is known about insect diversity and specialization. However, studying these larvae in a lab is proving difficult.

The larvae collected eventually died without reaching metamorphosis, suggesting that either recreating their natural habitat is extremely challenging or that some unknown element of the nest is crucial to their survival.

Now, the mystery isn’t just how this larva evolved—but what it will look like as an adult.

Images | IBE | Roger Vila | Current Biology

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