The fine structure of the Echthistus cognatus (Loew 1849) chorion was studied using both transmission (TEM) and scanning electron microscopes (SEM). Females were collected in the field and kept under laboratory conditions. Eggs were individually deposited in cotton batting. They were a light yellow color and elongated in shape after the deposition, with an average length of 1.5 mm and an average width of 0.4 mm. Except for the micropylar region, ridges extend all over the surface of the chorion. Aeropyles with different size and shape were present between ridges. There is a single micropylar opening at one pole of the egg. in the thin section, chorion forms a single layer. Chorionic ridges and sunken area are seen in the section.