n large animal swarm 

Perception +11; darkvision

Skills Acrobatics +11, Athletics +6, Stealth +11

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

AC  21; Fort +10, Ref +13, Will +8

HP 55; Immunities precision, swarm mind

Speed 25 feet

Scorpion Venom (poison) Saving Throw DC 18 Fortitude; Maximum Duration 6 rounds; Stage 1 1d6 poison damage (1 round); Stage 2 1d6 poison damage and enfeebled 1 (1 round)

Swarming Stings [>] Each enemy in the swarm's space takes 2d8 piercing damage (DC 21 basic Reflex save) and is exposed to scorpion venom.

Bestiary, page 285.