Nesting takes place between April and July. The female digs a cavity in a dry, sunny area of a bog, and lays her eggs in a grass tussock or on sphagnum moss. The nest is typically deep and around. Like most species of turtle, the bog turtle constructs its nest using its hind feet and claws. Most bog turtle eggs are laid in June. Pregnant females lay one to six eggs per clutch (mean of 3), and produce one clutch per year. A healthy female bog turtle can lay between 30 and 45 eggs in her lifetime, but many of the offspring do not survive to reach sexual maturity. Typically, older females lay more eggs than younger ones. The eggs are white, elliptical, and on average long and wide. After the eggs are laid, they are left to undergo an incubation period that lasts for 42 to 80 days. In colder climates, the eggs are incubated through the winter and hatch in the spring. The eggs are vulnerable during the incubation period, and often fall prey to mammals and birds. In addition, eggs may be jeopardized by flooding, frost, or various developmental problems. It is unknown how gender is determined in bog turtles.