Source : Webster's Revised Unabridged Dictionary (1913)

Ballooning spider \Bal*loon"ing spi"der\ (Zo["o]l.)
   A spider which has the habit of rising into the air. Many
   kinds ( esp. species of {Lycosa}) do this while young by
   ejecting threads of silk until the force of the wind upon
   them carries the spider aloft.