Recently, on one very humid morning, these mini 'pearl drops' were captured on a web of a grass orb weaver.
Apparently dew can not adhere to human hair but can on dry spider silk. A study published earlier this year in Nature (Zheng, Y. et al. Nature 463, 640-643 (2010) of the hackled orb weaver spider Uloborus walckenaerius web concluded the following:
“Dry spider silk forms a necklace-like structure. Two main fibres support a series of separate rounded 'puffs', each made up of tiny, randomly intertwined nanofibrils. When water vapour condenses onto these puffs, they shrink into densely packed knots, shaped like spindles (or two cones with their bases stuck together). Thinner connecting stretches of nanofibrils, separating the knots, become more apparent; these areas are called 'joints'. As water condenses on the web, droplets move towards the nearest spindle-knot, where they coalesce to form larger drops. The spindle-knots have a rough surface, because the fibrils within them are randomly interweaved. But the joints between the knots have a smooth texture, because their constituent fibrils run parallel to each other. It is this difference in roughness that helps water drops to slide towards the spindle-knots, sticking when they
The researchers then created their own spider silk using nylon fibers dipped in polymer solution and found when dry formed a similar structure. Their findings could lead to new materials for collecting water from the air.