The European blister beetle lays thousands of eggs in the spring. When they hatch, the bright-orange larvae shimmy up flower stems and sit in clumps, waiting for passing solitary bees to latch on to with hooklike appendages so they can grab a lift. Now researchers have found that these clumps give off a distinctly floral scent—making the larvae the first animal known to mimic a flower’s smell.
Ryan Alam, a chemist at the Max Planck Institute for Chemical Ecology in Germany, and his colleagues found that the larvae attract bees by emitting a collection of 17 scented compounds often found in flowers, including linalool oxide and lilac aldehyde. Once a larva has been airlifted to a bee’s nest, it feeds on the bees’ eggs and supplies of pollen and nectar. It stays there until it pupates and then leaves as an adult to restart the cycle.
In addition to attracting bees, the larvae’s perfume also draws other larvae, which could help them to form those flowerlike aggregations. The study was posted on the preprint server bioRxiv and hasn’t been peer-reviewed, but it “presents a convincing case that the beetle larvae are mimicking flowers chemically, and perhaps visually, so as to deceive and attract bees,” says Jim McLean, an evolutionary biologist at Macquarie University in Australia, who was not involved in the study.
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Animals such as the orchid mantis mimic the look of flowers, and the corpse flower emits a smell like rotting meat to attract insects, but these beetles add a new strategy to the mimicry playbook, Alam says.
Dmitry Telnov, an entomologist at the Natural History Museum in London, who was also not involved in the study, notes that a different blister beetle species in the U.S. can mimic the sex pheromones of host bees. Mimicking smells “might be an evolutionary approach used by blister beetles to attract specific species,” he says, “which is absolutely surprising.”