The current situation with the Zerg

Tier 0: Common Soldier Worm

First Order: Elite Soldier Bugs

Second Order: Black Iron Worm, Wind Splitting Flying Worm

Third Order: Ground Flame Worm, Brain-Eating Worm, Big Horned Worm

Fourth Order: Corpse Eater Spider

Fifth Order: Devouring Earth Dragon

Insect King Guard: Wormman (Advanced Insect King), Ghost-Face Shadow Insect (Intermediate and Low Insect King)

Except for the Bugs, all other Bugs have a chance to advance or evolve!