n large animal swarm 

Perception +8; darkvision

Skills Acrobatics +6, Stealth +8

Str +0 Dex +4 Con +3 Int -5 Wis +0 Cha -5

AC  19; Fort +8, Ref +11, Will +5

HP 25; Immunities precision, swarm mind; Weaknesses area damage 5, splash damage

Speed 5 feet, fly 25 feet

Pyrexic Malaria (disease) The victim can't reduce its sickened condition while it's affected by pyrexic malaria Saving Throw DC 20 Fortitude; Onset 4 days; Stage 1 sickened 1 (1 day); Stage 2 enfeebled 1 and sickened 1 (1 day); Stage 3 as stage 2 (1 day); Stage 4 unconscious (1 day)

Swarming Bites [>] Each enemy in the swarm's space takes 1d6 piercing damage (DC 20 basic Reflex save) and is exposed to pyrexic malaria. Creatures that fail the saving throw also take 1d4 persistent bleed damage.

Bestiary 2, page 175.