Charlotte's Web, the E. B. White childhood classic, ends with Wilbur the pig eagerly waiting for Charlotte's baby spiders to emerge from their egg sac in spring. When they finally crawl out, they do something that seems pretty amazing to anyone not familiar with how some spiders travel long distances: they fly away. “One spider climbed to the top of the fence,” White wrote. “Then it did something that came as a great surprise to Wilbur. The spider stood on its head, pointed its spinnerets in the air, and let loose a cloud of fine silk. The silk formed a balloon. As Wilbur watched, the spider let go of the fence and rose into the air.… ‘Wait a minute!’ screamed Wilbur. ‘Where do you think you're going?’ But the spider was already out of sight.”
Charlotte's hatchlings were “ballooning,” which is the method that some spiders, especially baby spiders, use to disperse themselves through nature. Richard Bradley, an entomologist at Ohio State University, says that the phenomenon happens all over the country in spring, summer and fall but that it is tricky to catch. “The key is weather,” he wrote in an e-mail. “You need a relatively calm air or a slight breeze—ballooning doesn't happen often in wind. The rising air currents created by the sun heating the ground are the launching force for these tiny flights.” Bradley recommends going to “exposed places with prominent launchpads,” such as fence posts, stumps, small bushes or even an unmown lawn on a cool, clear morning, and looking for silk lines or lots of webbing. “If you find this, you might be in for a treat,” he says.
Adapted from Budding Scientist at blogs.ScientificAmerican.com/budding-scientist
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