These tubes are similar to a kidney. The salvary glands in tsetse flies are narrow but extremely long, extending back into the abdominal cavity. In the head the glands form a common salivary duct which passes down the hypopharynx. This method involves the retention of a single egg which develops to the third larval stage before being deposited. Adults of other fly species also do this, such as Sarcophaga but in these the first stage larval are deposited.
Reproduction begins in a newly emerged female when an ova is released from the right ovary.
From the ovary it passes down the oviduct to the uterus. Here the micropyle, which is a small aperture at one end of the egg, comes into a position with the opening of the spermathecal duct. This duct is controlled by a sphincter and opens only at ovulation. The eggs within the uterus hatches in 3-4 days giving rise to the first stage larva. The larva exits the egg using a special labral tooth and once out the remains of the egg are shed through the vaginal opening.