Bugs

Flies: Bigger than Old World flies, but not giant by any means. Pieces of them are used for fishing bait.
  Cockroaches: Unchanged from Old World roaches. Kind of astounding, actually.
  Fleas: Large, persistent, and bloodthirsty. Easily killed by specialized poisons, or just by lopping off their heads. Not quite as hardy as their Old World counterparts, but just as pesky.
  Mosquitos: Giant by Old World standards, but by no means huge. Pesky parasites, who lay eggs in corpses rather than in water, since their larva would be eaten instantly.
  Giant Roaches: Cockroaches, but giant. A little more intelligent, and sometimes used in races. Cleanup crew of The Valley.
  Burrowers: Giant Worms. Peaceful creatures, but terrifying to encounter if you've never seen one on the surface.