The Collaborative International Dictionary of English v.0.48:

Swarm \Swarm\, v. i. [imp. & p. p. Swarmed; p. pr. & vb. n.
   Swarming.]
   1. To collect, and depart from a hive by flight in a body; --
      said of bees; as, bees swarm in warm, clear days in
      summer.
      [1913 Webster]

   2. To appear or collect in a crowd; to throng together; to
      congregate in a multitude. --Chaucer.
      [1913 Webster]

   3. To be crowded; to be thronged with a multitude of beings
      in motion.
      [1913 Webster]

            Every place swarms with soldiers.     --Spenser.
      [1913 Webster]

   4. To abound; to be filled (with). --Atterbury.
      [1913 Webster]

   5. To breed multitudes.
      [1913 Webster]

            Not so thick swarmed once the soil
            Bedropped with blood of Gorgon.       --Milton.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

107 Moby Thesaurus words for "swarming":
   abounding, abundant, alive with, blooming, bountiful, bristling,
   bursting, bursting out, close, compact, copious, crammed, crawling,
   creative, creeping, crowded, crowding, dense, emigration,
   expatriation, exuberant, fecund, fertile, firm, flight,
   flourishing, fructiferous, fruitful, full, generous, honeycombed,
   immigration, in profusion, in-migration, infestation,
   intermigration, invasion, jam-packed, jammed, lavish, lousiness,
   lush, luxuriant, migration, out-migration, overabundant,
   overbounteous, overcopious, overexuberant, overflowing,
   overgenerous, overlavish, overliberal, overluxuriant, overmuch,
   overnumerous, overplenteous, overplentiful, overplenty,
   overpopulated, overpopulous, overprolific, overrunning,
   overspreading, overswarming, packed, passage, permeated, plague,
   plenteous, plentiful, plethoric, populous, pregnant, prodigal,
   productive, profuse, proliferating, proliferous, prolific,
   pullulating, ravage, remigration, replete, rich, rife, riotous,
   run, saturated, seminal, serried, shot through, solid, studded,
   superabundant, swarm, teeming, thick, thick as hail, thick with,
   thick-coming, thriving, thronged, thronging, transmigration, trek,
   uberous