I think the bugs in the Telepath Universe are eusocial like ants and bees. The Bug Queens, like ant queens and bee queens, are the mothers of all the bugs. Shadow Bugs and Nymphs are the same species, but they each have different roles in the colony. Bugs are in almost every region of Cera Bella. Each region has its own Bug Queen and its own colony. There is likely three bug queens; one in the Deeper Downs, one in the Great Forest, and one in the Ashwan Desert. When a queen dies, one of her pupa would grow to replace her.
The Bug Queen is the mother of all bugs. She lays the eggs that are the first stage in all the bugs' lives. All the eggs will hatch to become larva. Most larvas will become pupas and evolve into Nymphs, but some specially feed larva will become Bug Queens after their pupa stage. When the larvas metamorphose into Nymphs, its newly developed brain gives it psy capabilities like Mega Shield. Nymphs are responsible for taking care of eggs and larva. They are also in charge of healing and shielding other members of the colony. A small number of Nymphs will mate with the Bug Queen. After the Nymphs stage is the Shadow Bug stage. When they become Shadow Bugs, their brains become more primitive and incapable of using shields. The Nymph's blue exoskeleton is molted for a thinner black shell. The new exoskeleton may not be as strong, but it helps the predator camouflage into its dark environment. While the Nymph stage is responsible for healing and nurturing the colonies, the Shadow Bug stage is suppose to hunt for food, to protect the colony, and to dig more territory. As predators, Shadow Bugs are better at attacking then the other stages (except for the Queen).