A case of biological mimicry has been spotted in Ceratocaryum argenteum, a South African plant that tricks dung beetles into spreading its stinky seeds. Photograph by Hoberman Collection / UIG via Getty

Read enough about the dung beetle and a picture of its character emerges: patient, optimistic, uncomplaining. It is capable of moving many times its own weight in excrement, which it rolls across the ground in remarkably straight lines, sometimes using the Milky Way to navigate. (The Ancient Egyptians perhaps sensed this celestial affinity: the scarab-headed god Khepera was said to nudge the sun across the sky as a beetle does its dung.) The insect is also remarkable for its tireless dancing, by which it reorients itself after its path has been disrupted in some way. “Where most animals would try to escape, or cease to behave in this situation, the dung beetles accept these disruptions and will continue to roll and dance all day long,” the zoologist Emily Baird told National Geographic in 2012.

It seems inevitable that, in this cutthroat Darwinian world, some species would find a way to exploit the dung beetle’s good nature, and new research suggests that Ceratocaryum argenteum, a rush-like flowering plant native to South Africa, does just that. The plant produces large, round nuts that are strikingly similar in appearance, smell, and chemical composition to antelope droppings (in particular those of the eland and the bontebok), which the dung beetles accordingly roll away and bury, effectively sowing a new generation of C. argenteum. Although scientists have observed dung beetles providing similar services elsewhere in the plant kingdom—as, for example, when the dung happens to contain fruit seeds—this is the first known case of a dung beetle helping and not ending up with any dung.

Jeremy Midgley, the lead author of the study, which was published on Monday, in the journal Nature Plants, first became interested in Ceratocaryum nuts because of their large size. This quality, he originally hypothesized, might make them attractive to rodents. From the beginning, he told me, the nuts’ distinctive smell was “very apparent and was confusing,” but he thought there was a chance that other animals might not find it off-putting. Using motion-sensitive cameras, Midgley and his colleagues recorded two hundred and fourteen instances of mice interacting with the nuts. In this footage, he said, the general mouse attitude appeared to be “either disinterested or even repelled.” But, by triggering the cameras, the mice revealed something that the biologists might otherwise never have noticed: dung beetles industriously rolling the nuts away. Suddenly, Midgley said, “the color, shape, size, and smell made sense.” The scientists revised their experiment, setting out a large number of Ceratocaryum nuts after the rain (a time favored by dung beetles) and equipping them with fluorescent thread markers that enabled them to be tracked with a special flashlight. Of the sixty-six nuts that were successfully recovered, fifty-three had been buried, beetle-style.

The phenomenon of biological mimicry is rarer in plants than it is in animals. Most cases involve sexual mimicry in flowers; some members of the orchid genus Ophrys, for instance, seduce male bees into pollinating them by imitating the look, smell, and feel of a female bee. The use of deception for seed dispersal is less common. “The vast majority of seed-dispersal strategies involve wind, water, hitchhiking, or luring animals with an honest reward,” Thor Hanson, the author of The Triumph of Seeds, told me. He cited only a handful of counterexamples: one hoax, for example, targets ants, capitalizing on the tendency of certain honest seeds to grow a fatty appendage that ants can eat. Other, dishonest, inedible seeds mimic the chemistry of the fatty appendage, tricking ants into carrying them away in hopes of eating them later. Despite the rarity of such cons, Hanson said that he was “not surprised in the least” to hear of the dung-beetle research, which he warmly saluted. “This idea of mimicking dung crosses into interesting new territory,” he said in an e-mail. “It’s reminiscent of the mimicry that goes on in pollination, where flowers can look and smell like rotten meat (to attract flies).”

As Midgley noted, in a press release that accompanied the Ceratocaryum study, “We still have much to learn about the dynamics of such fecal mimicry.” He is curious, for instance, how the hoax would work in other environments. Its success depends on just the right balance of dung to beetles: if there’s too much dung around and the beetles have too much choice, they might become too discerning; if there’s too little dung, there probably aren’t enough beetles to bury the nuts in any significant quantity. But it also depends on the character of the beetles. Consider the condition of the buried nuts, which Midgley and his colleagues were able to recover within hours of burial: “In no case did we capture any dung beetles or observe any beetle eggs on seeds or any damage to the seeds,” they write. Having attempted, unsuccessfully, to eat or oviposit in the seeds, it seems that the beetles quietly accepted the deception and moved on with their lives.