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The irresistible scent of dead arthropods

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Some scents can’t help but draw us into a room— freshly-baked chocolate-chip cookies, coffee, the corpses of rotting arthropods… Maybe the latter isn’t especially appealing to us humans, but it’s irresistible to certain insects. And there’s a flower that uses this fact to its advantage.

Like many members of the plant kingdom, Aristolochia microstoma, a Greek plant with strongly scented tube-like flowers that grow at ground level, relies on insects to pollinate it. Unfortunately, its flowers don’t make this easy. Their male and female organs are situated deep inside its tube-like flowers, and it’s a tough sell getting insects to enter. Still, some insects do just that. They crawl inside the flower, deposit the pollen they brought with them, at which point they’re trapped inside until the flower releases pollen of its own. Only then is the insect free to leave, hopefully covered in new pollen and primed to pollinate another Aristolochia microstoma flower.

When studying what kinds of insects pollinate these plants, scientists noticed that the most frequent visitors were flies from the Phoridae family. Some members of this family of flies are known to feed and lay their eggs on carrion and other decaying matter. After analyzing the scent emitted by the plant’s flowers, the scientists noticed it was very similar to the scent of dead beetles. Their theory is that the plant emits the scent of arthropod corpses to attract the flies that pollinate it. It’s hard to imagine a scent like that having such a strong appeal, but chocolate-chip cookies just don’t cut it for everyone.

Two tan and brown flies sit on a bright green leaf

The Aristolochia microstoma plant attracts flies like these from the Phoridae family (Katja Schulz / Wikimedia Commons)

Some scents can’t help but draw us into a room— freshly-baked chocolate-chip cookies, coffee, the corpses of rotting arthropods…

Maybe the latter isn’t especially appealing to us humans, but it’s irresistible to certain insects. And there’s a flower that uses this fact to its advantage.

Like many members of the plant kingdom, Aristolochia microstoma, a Greek plant with strongly scented tube-like flowers that grow at ground level, relies on insects to pollinate it. Unfortunately, its flowers don’t make this easy. Their male and female organs are situated deep inside its tube-like flowers, and it’s a tough sell getting insects to enter.

Still, some insects do just that. They crawl inside the flower, deposit the pollen they brought with them, at which point they’re trapped inside until the flower releases pollen of its own. Only then is the insect free to leave, hopefully covered in new pollen and primed to pollinate another Aristolochia microstoma flower.

When studying what kinds of insects pollinate these plants, scientists noticed that the most frequent visitors were flies from the Phoridae family. Some members of this family of flies are known to feed and lay their eggs on carrion and other decaying matter. After analyzing the scent emitted by the plant’s flowers, the scientists noticed it was very similar to the scent of dead beetles. Their theory is that the plant emits the scent of arthropod corpses to attract the flies that pollinate it.

It’s hard to imagine a scent like that having such a strong appeal, but chocolate-chip cookies just don’t cut it for everyone.

Reviewer: Lynda Delph, Indiana University

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