This is the final candling to check on the health of the duck embryos before hatching. The ducklings should hatch in 24-72 hours. The incubator will remain closed until the ducklings hatch and dry. This year we have 2 Welsh Harlequins and 4 Black Runners eggs. According to the farm we got the eggs from, the Welsh have a 28 day incubation period and the Runners 28.5 days.