Found in swamps on Island and Lost Island. Kill one to get the pheromones.

When you find a female, take it to low health then feed a large creature the pheromone. She will inject her larva. Your creature will then have cravings for random items including Element, Giga eggs, and Carch eggs. Fulfilling cravings gives a better level baby. When the offspring is ready, it will kill the host, so don’t use anything you aren’t willing to lose.