n large animal swarm 

Perception +9; darkvision, tremorsense (imprecise) 30 feet

Skills Acrobatics +9, Athletics +7, Stealth +9

Str +2 Dex +4 Con +3 Int -5 Wis +0 Cha -4

AC  18; Fort +8, Ref +11, Will +5

HP 30; Immunities precision, swarm mind; Weaknesses area damage 5, splash damage 5

Speed 30 feet, climb 30 feet

Centipede Swarm Venom (poison) Saving Throw DC 20 Fortitude; Maximum Duration 6 rounds; Stage 1 1d6 poison damage and flat-footed (1 round); Stage 2 1d8 poison damage, clumsy 1, and flat-footed (1 round)

Swarming Bites [>] Each enemy in the swarm's space takes 1d8 piercing damage (DC 20 basic Reflex save) plus centipede swarm venom.

Bestiary, page 61.