CR: 3

Hit Dice: 3d10+6 (29 hp)

Initiative: +6 (+2 Dex)

Speed: 50 ft. (10 squares), burrow 10 ft.

Armour Class: 16 (+2 Dex, +4 natural), touch 12, flat-footed 14

CMB/ CMD +8/ +18

Attack: 2 x Claw +8  (1d6+4/18-20/x3)

Full Attack: 2 claws +8 melee (1d6+4/18-20/x3) and bite +7 melee (1d4+4)

Space/Reach: 5 ft./5 ft.

Special Attacks: Rake (2d6+6), Pounce

Special Qualities: Zerg Traits

Saves: Fort +5, Ref +4, Will +2

Abilities: Str 16, Dex 17, Con 19, Int 2, Wis 13, Cha 7

Skills: Stealth +5 (+9 underground), Perception +5 (+8 underground)

Feats: Alertness, Cleave,  Improved Critical, Improved Initiative, Run, Iron Will, Nimble Moves, Weapon Focus (claw)

Organization: Solitary, pair, pack (6-15), horde (20-50 and 5-7 Hydralisks), or brood (100-200, 24-37 Hydralisks and 3-7 Ultralisks)

This creature is about the size of a man, with a short tail and tough carapace. Its back legs are long, while its front legs end in sickle-like claws. Beneath its head rest two equally sharp fangs, and it chitters and jumps about restlessly. 

Combat

The Zerglings are little more than feral animals. Mutated by the Zerg to be more efficient killers, the voracious creatures are capable of ripping a larger creature to shreds with their razor-limb sickles and sharp fangs.

Improved Critical (Ex): Due to its sickle-bladed forelegs, a Zergling's claw attack threatens a critical hit on a natural attack roll of 18–20, dealing triple damage on a successful critical hit.

Rake (Ex): If a Zergling begins its turn grappling with a foe, it may make two claw attacks at a +4 bonus. These attacks deals 2d6+1 points of damage.

Skills: Zerglings have a +4 racial bonus to Perception & Stealth checks while underground.

Pounce: