The egg, all four larval instars, and pupa of Culicoides sonorensis Wirth and Jones (Diptera: Ceratopogonidae) are described and imaged using a compound microscope and scanning electron microscopy. The differences between the larval instars have also been noted. The swimming speeds of the larvae as well as the location of the pupae and their responses to both changes in the waterline and prolonged submersion underwater have also been examined.