Spiders lure bees for dinner by making flowers look flashier

10 July 2017

By Katie Langin

Ambush hunters normally rely on the element of surprise, opting to stay hidden until the moment of attack. But some spiders go for a flashier strategy. They reflect UV light, which makes the flowers they sit on appealing to bees – a bizarre strategy that has evolved multiple times in crab spiders, which ambush their prey instead of catching it in webs.

Felipe Gawryszewski at the Federal University of Goiás in Brazil and his team collected individuals from 68 species of crab spider in Australia, Europe and Malaysia. All of the species hunted insects using a sit, wait and pounce strategy, but some did so on drab substrates like bark and leaves while others hunted on flowers.

Using genetic information from all these species, the team pieced together a “family tree”, which showed that the flower-based hunting strategy evolved multiple times. What’s more, flower-dwelling crab spiders reflected more UV light than non-flower dwellers.

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This appears to be an effective hunting strategy as bees are more likely to visit flowers when UV-reflecting spiders are perched atop them.

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