(sperm-storing organ) can store the sperm for a long period of time before fertilizing the eggs, but species without the organ fertilize their eggs shortly after mating. The female carries the fertilized eggs in a brood pouch attached to her abdomen.

Between two and 50 young are hatched in a single brood, with more than one brood per year possible. The young go through three molts called the protonymph, deutonymph, and tritonymph. The