n large animal swarm 

Perception +8

Skills Acrobatics +8, Thievery +8

Str +0 Dex +4 Con +0 Int -4 Wis +2 Cha +0

AC  16; Fort +6, Ref +10, Will +6

HP 20; Immunities precision, swarm mind; Weaknesses area damage 3, splash damage 3; Resistances piercing 3, slashing 3

Cacophony (auditory, aura) 20 feet. The monkeys' awful racket of screeches and howls drowns out other sounds. Any creature performing an auditory action in the area must yell over the din, requiring a successful DC 15 Fortitude save or Performance check to project loudly enough; on a failure, the action is lost.

Speed 25 feet, climb 20 feet

Ransack [>>] The swarm rummages through the possessions of a single creature within its space, attempting a Thievery check against the creature's Reflex DC. On a success, the monkeys take one random item of negligible Bulk that the creature is wearing but not closely guarding, such as an object in a loosely carried pouch.

Swarming Bites [>] Each creature in the swarm's space takes 1d8 piercing damage (DC 18 basic Reflex save).

Bestiary 3, page 172.