Blending in with the background is often the best way to lay a trap. So, if you're luring a tasty snack into a tight corner, you'd better keep a low profile. But En-Cheng Yang and I-Min Tso were puzzled by a spider species, Nephila pilipes, on Taiwan's tropical Lan-Yu Island. Yang explains that Nephila occur in one of two guises. The majority are poorly camouflaged with bright yellow markings on their legs and abdomen, while the remainder are covered in dark melanic markings. But the brightly marked spiders seemed to have no problems luring hapless bees and flies into their webs. What was going on? How was this brightly coloured arachnid such a successful hunter when it appeared to lack the necessary camouflage? Yang and Tso decided to look at the lurid creatures from the perspective of one of the spider's favourite meals: the bee(p. 2631). But first they needed to monitor the spiders' hunting prowess, just to be sure that they really were more successful than their less colourful relations.

After flying southeast to the island, the team headed into the thick tropical forest to watch the spiders and their webs at work. Taking up residence in one of the island's isolated valleys, Tso, Yang and Chih-Wei Lin monitored the hourly catch rates of 18 brightly coloured Nephila and 5 melanic Nephila. Sure enough, the conspicuous spiders were twice as successful at trapping prey as the duller spiders. But why weren't the victims avoiding the lethal traps? After all, they should be able to see the spider's vivid markings.

Yang explains that, thanks to Lars Chittka, there was a good computational model of the bee's visual system that he and his colleagues could use to calculate the victim's view of the hungry predator. But first they needed to measure the spectra reflected from every millimetre of the spider's surfaces,and the visual conditions beneath the forest's canopy. Having successfully measured the background light environment throughout the day, the team returned to Taichung with eight spiders to measure their reflection spectra under more controlled conditions. Combining the two measurements with knowledge of the bee's visual photosensitivity in a Matlab calculation, the team were finally ready to calculate a bee's eye view of Nephila.

But the team were astonished when they realised that from a bee's perspective, Nephila looked nothing like a spider! In fact, Nephila's coloured markings might even look like an attractive flower to the approaching victim. Which could explain the spiders hunting success relative to their duller cousins, which build their webs in dark corners. Yang suspects that the melanic spider's victims simply blunder into the inconspicuous webs, while the coloured spiders lure their prey in with attractive bait.

Tso, I-M., Lin, C.-W. and Yang, E.-C. (
2004
). Colourful orb-weaving spiders, Nephila pilipes, through a bee's eyes.
J. Exp. Biol.
207
,
2631
-2637.