Butterflies of Sri Lanka

Genus Eurema - Similar Species

All the Grass Yellows are very similar to each other and show considerable geographic and seasonal variation in appearance. This makes identification based on external characteristics somewhat difficult. The summary of characteristics given below are therefore general guidelines for their identification. To deal with aberrations or extreme seasonal forms it would be necessary to study their genitalia.

Common Grass Yellow

1.	Under side forewing - Not more than two spots located towards the basal half of the cell.
2.	Forewing margins entire and not wavy.
3.	The lower extremity of the black border of the forewing never subtended by yellow.
4.	Upper side of the forewing - The boundary between the inner yellow area and the outer black area resembles a dog's face.

Three Spot Grass Yellow

1.	Under side forewing - Three spots located towards the basal half of the cell.
2.	Forewing outer margin distinctly crenulate (wavy).
3.	Lower extremity of the black border of the forewing partially subtended by yellow. The black border does not run along vein 1A to any appreciable distance.
4.	A large rust colored smudge often found on the underside of the forewing apex. It is commonest in females and touches both the outer and costal margins.
5.	Upper side forewing - Like the Common Grass Yellow, the border between the yellow and black areas traces a dog's face..

The Small Grass Yellow

1.	The line traced between the black and yellow area of the forewing does not resemble the outline of a dog's face. Instead, it is wavy and looks like the knuckles of the hand and starts on the costal margin and ends on the lower margin. This feature distinguishes it from the One Spot Grass Yellow, the Three Spot Grass Yellow and the Common Grass Yellow.
2	Under side - Almost always with dark spots. A few fine faint indistinct zigzag lines of black scales. This feature distinguishes it from the Spotless Grass Yellow.

The Spotless Grass Yellow

1.	Upper side forewing - The line that separates the yellow and the black areas is similar to the one in the Small Grass Yellow.
2.	Under side - Fewest markings of any Grass Yellow. Always has an indistinct dark line at the center of the wing, often a second parallel line below.

The One Spot Grass Yellow

1.	Distinctly rounded forewings.
2.	Underside of the forewing - Well marked streak at the base of the cell.
3.	Upper side hind wing - The outer margin is edged with a fine black line that widens into small triangular areas where the veins meet the termen.