GrrlScientist is an evolutionary biologist, ornithologist, aviculturist, birder and freelance science and nature writer. A native of the Pacific Northwest, she relocated from Seattle to NYC with her parrots after earning a BS in Microbiology (emphasis in Virology) and PhD in Zoology (Ornithology) from the University of Washington. In NYC, she was the Chapman Postdoctoral Fellow at the American Museum of Natural History for two years, pursuing part of her "dream" research project by reconstructing a molecular phylogeny of the parrots of the South Pacific islands. GrrlScientist has written a blog about science since 4 August 2004 (the early years are archived 
Brenthia hexaselena, a species of metalmark moth,
flares its hind wings (HW) and spreads its forewings (FW) to mimic a jumping spider.
In lab trials, spiders caught 6 percent of the metalmark moths presented to them, as opposed to 62 percent of other moth species. What's more, the spiders sometimes made territorial gestures at the metalmarks -- and occasionally backed away.
For most moths, the sight of a jumping spider makes them panic as they try to escape its lethal pounce. But not so for metalmark moths in the genus Brenthia. These moths stand their ground with hind wings flared and forewings held above the body at a slight angle.
These moths are relying on mimicry to save their lives.
In that pose, the moth looks like a jumping spider, said Jadranka Rota, a graduate biology student at the University of Connecticut.
"That will actually save [the moth's] life," she said.
"The spider needs to act pretty quickly. Deciding whether the moth is potential prey or another jumping spider could take enough time to offer an advantage, in comparison to other moths."
Such mimicry usually allows the metalmark moth enough time for escape.
These experiments indicate that jumping spider mimicry is more widespread than previously appreciated, and jumping spiders are probably an important selective pressure shaping the evolution of diurnal insects that perch on vegetation.
The moth (upper image) mimics jumping spiders (lower image) with wing markings, wing positioning, posture, and movement (drawing by Virginia Wagner).
These moths survive encounters with jumping spiders more often than controls.
Moreover, jumping spiders respond to them with territorial displays that are normally directed towards other jumping spiders, indicating that Brenthia moths are being mistakenly recognized as jumping spiders, and not as potential prey.
Original paper, images.
Cited quotes.
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Comments
coolest.
mimicry.
evah.
Posted by: JanieBelle | February 16, 2007 10:31 PM
Very interesting! The most convincing spider mimic that I've yet seen and photographed was a species of Rhagoletis fly that has wing patterning that looks like the raised front legs of a jumping spider. Further, it walks around waving its wings and hopping like a jumping spider, which adds to the effectiveness of its mimicry. When I've found these flies, it's almost impossible for me not to feel a "reaction" as though I'm seeing a spider. There's a photo and a bit about this fly on a post I wrote about insect imposters awhile back -- there are some other interesting insects in that post as well.. moths and flies that look like wasps, etc...
Posted by: bev | February 18, 2007 7:05 AM
Wow - that is so cool! I have never heard of this particular mimicry example before.
Posted by: Jenn | March 9, 2007 3:03 PM
That is a scary moth... but I have seen a caterpillar that looks exactly like a miniature snake
Posted by: Faith | December 11, 2008 7:52 AM