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Ballooning is a term to describe the way many spiders, as well as certain mites and some caterpillars disperse through the air.

Many small spiders use silk threads for ballooning. They extrude several threads into the air and let themselves become carried away with upward winds. Tiptoeing behavior occurs as a prelude to ballooning: The spider stands on raised legs with the abdomen pointed upwards. Although most rides will end a few meters later, it seems to be a common way for spiders to invade islands. Many sailors have reported that spiders have been caught in their ship's sails, even when far from land. (Heimer 1988)

It is generally thought that most spiders heavier than 1 mg are not likely to use ballooning (Suter 1999). Also, because many individuals die during ballooning, it is more unlikely that adults will do it than spiderlings. However, adult females of several social Stegodyphus species (S. dumicola and S. mimosarum), weighing more than 100 mg and with a body size of up to 14 mm, have been observed ballooning using rising thermals on hot days without wind. These spiders used tens to hundreds of silk strands, which formed a triangular sheet with a length and width of about one meter. (Schneider 2001)

• Heimer, S. (1988): Wunderbare Welt der Spinnen. Urania-Verlag Leipzig. ISBN 3-332-00210-4
• Suter, R.B. (1999): An aerial lottery: The physics of ballooning in a chaotic atmosphere. Journal of Arachnology 27: 281-293. PDF
• Schneider, J.M., Roos, J., Lubin, Y. & Henschel, J.R. (2001): Dispersal of Stegodyphus dumicola (Araneae, Eresidae): They do balloon after all! The Journal of Arachnology 29: 114-116. PDF

• Dean, D.A. & Sterling, W.L. (1985): Size of ballooning spiders at two locations in eastern Texas. J. Arachnol. 13: 111-120. PDF