Larva
Small Aberration (Zerg)
Hit Dice: 1d8 (4 hp)
Initiative: +0
Speed: 10 ft. (2 squares)
Armour Class: 32 (+1 size, +21 natural), touch 11, flat-footed 32
Base Attack/Grapple: +0/-6
Attack: --
Full Attack: --
Space/Reach: 5 ft./5 ft.
Special Attacks: --
Special Qualities: Darkvision 60 ft., immunity to poison and cold, resistance to acid and eletricity 15, morph, Zerg traits.
Saves: Fort +0, Ref +0, Will +3
Abilities: Str 7, Dex 11, Con 11, Int 1, Wis 13, Cha 7
Skills: Hide +5, Listen +5
Feats: Improved Natural Armor
Environment: Any
Organization: Solitary, pair, or group (3)
Challenge Rating: 1/4
Treasure: None
Alignment: Lawful evil
Advancement: --
Level Adjustment: --

   This looks similiar to a large caterpillar. It possess many legs, small spikes on its back, three pairs of large compound eyes, and two jagged mandibles.

Description
   The closest creatures to the original Zerg insectoids are the Zerg Larvae. Although their size and toughness were greatly boosted by the Xel'Naga during their experiments, they still possess the two traits that originally intrigued the ancient masters: genetic versatility and psychic sensitivity. Each larva contains within it the genetic makeup of every other Zerg breed. A young hive will only have the genetic code for the most basic of Zerg breeds, such as the Drone, but as it grows and develops new structures the larvae can expand their library of genetic strains. With a command from the Overmind, the larvae will enter a pupal state and begin the metamorphosis into whichever breed is required by the hive.

Combat
   The sole purpose of these creatures is to mutate into more advanced strains of Zerg - though they have a surprisingly hard exoskeleton, they are essentially helpless in combat.
   Morph (Ex): A Larva can transform into more advanced types of Zerg, as determined by how much genetic information is available to the hive it came from. During transformation, the larva is increased inside an egg (hardness 30, HP 40). The transformation process takes one round per hit die of the new form the Larva is assuming. Zerglings and Scourge hatch two from an egg.