How does a fly larva sneak into a termite nest? With a butt shaped like a termites head, obviously. An international team of researchers in Morocco has discovered blow fly larvae not just living but thriving inside a termite colony. This potentially new species has evolved remarkable adaptations to evade the colonys soldier termites, which swiftly dismember intruders. Its survival tricks include a termite-head-shaped derriere, antennae-like tentacles, and the ability to mimic the colonys distinctive scent. The strategy is clearly working because the researchers observed the termites caring for the intruders. This is a chance finding. In our research group we mainly study butterflies and ants. As it had rained a lot and the butterflies were not flying, we looked for ants. When we lifted a stone we found a termite mound with three fly larvae that we had never seen before, Roger Vila, a biologist at the Institute of Evolutionary Biology, said in a Spanish National Research Council statement. It must be an extremely rare species, because we have made three more expeditions in that area and, despite lifting hundreds of stones, we found only two more flies, together, in another termite mound, he added. As detailed in a study published Monday in the journal Current Biology, the researchers identified a so-called termite mask on the rear end of the blow fly larvae: a head-shaped appendage complete with non-functional antennae and palps (appendages near the mouth related to touch and taste), all exactly the same size as those of large harvester termites. As if that wasnt impressive enough, the larvaes breathing holes look like eyes on the termite mask. Most termites live several meters deep and have no visual perception. However, harvester termites come out at dusk to collect grass, so they have functional eyes that the larvae are able to mimic with their spiracles [breathing holes], Vila explained.As termites have not yet invented artificial lighting (and seeing how easily theyre fooled, they wont for a very long time), members of the same colony identify their fellows by using their antennae to smell and touch each other. But the larvae clearly already know this, since Vila and his colleagues also identified numerous other antenna-like tentacles along their bodies, which they suggest help the baby flies communicate with (trick) more than one termite at a time. Moreover, they have also found a way to mimic the termites smell. We quantified the chemical composition of these larvae and the result is surprising: they are indistinguishable from the termites in the colony where they live; they smell exactly the same, said Vila. In addition, the larvae and termites in a particular colony have slight differences in their chemical profile that differentiate them from other termite mounds. This odor is key to interacting with the termites and benefiting from their communal life. It is a chemical disguise.And benefit they do. After transferring the larvae and termite colony into a lab, the researchers noted that the larvae usually hung out in the most trafficked area of the termite nest. There, their unknowing termite hosts preened them and may have even fed them, though the researchers admit that this latter behavior needs to be confirmed. Additionally, the larvae we studied eventually died without metamorphosing, so there may be elements of the nest and the symbiotic relationship between the termites and the flies that we were unable to transfer to the laboratory. Their diet is currently unknown, and their adult form remains a mystery, Vila pointed out. The researchers noted that humpback flies also demonstrate masking behaviors, with one main difference: they mimic termites as adults, not in their larval stages. Furthermore, the common ancestor of blow flies and humpback flies dates back more than 150 million years, much further than that which separates humans from mice. We are therefore confident that we have discovered a new case of social integration evolution, said Vila.The researchers also revealed that, within the blow fly family, the new fly is a member of the genus Rhyncomya. As scientists are not aware of any other Rhyncomya flies demonstrating this sort of unique lifestyle, the researchers consequently speculate that the species must have evolved quickly. Ultimately, the researchers make the rather unique claim of being the first to observe a blow fly living in disguise among termitessuccessfully, anyway. Who knows how many failed pretenders were dismembered by soldier termites before they got the camouflage right.