Female Lusus Equivalent, where do trolls come from?

Trolls hatch from eggs laid by the Mother Grub. Adult trolls fill filial buckets with their reproductive fluids and the Imperial Drones bring these fluids to the Mother Grub. She combines the fluids all into one incestuous slurry and lays thousands of eggs at once. They hatch and appear as small caterpillars with heads but later pupate into a humanoid.