01 February 2020

Emigrants of Singapore

Emigrants of Singapore
Featuring the Catopsilia butterfly species

A Mottled Emigrant feeding on the flowers of the Javanese Ixora (Ixora javanica)

Amongst the bright and noticeable urban butterfly species that are often spotted by nature enthusiasts, is a group of butterflies called "Emigrants". These species belong to the Pieridae family and classifed under the genus Catopsilia. They are medium-sized, fast-flying butterflies that are often seen in Singapore's urban parks and gardens.

An Orange Emigrant feeding on the flowers of Lantana camara

Collectively, the three species can be considered common urban butterflies that are regularly seen flying all over the island, sometimes even in the heart of the built-up Central Business District of Singapore. The three species, Lemon Emigrant, Orange Emigrant and Mottled Emigrant show migratory habits, particularly the Lemon Emigrant, hence their English common names.

A Lemon Emigrant f-hilaria feeding on the flowers of Lantana camara

If my memory serves me well, in the late 80's/90's I have observed many individuals of the Lemon Emigrant flying in one direction in the morning, and then in the reverse direction in the late afternoon. Since then, I have never seen this phenomenon again in recent years. The Orange and Mottled Emigrants do not seem to display this behaviour of mass 'migrations'.

A mating pair of Orange Emigrants

The Orange and Mottled Emigrants are single-formed species, with the morphological features of the butterflies quite consistent in both species. Males and females have subtle differences - enough to distinguish between the sexes if they stop long enough to be examined closely. The Lemon Emigrant, however, has multiple forms in both the males and females and has a wider variety of distinguishing features compared to its two cousins.

1) The Lemon Emigrant (Catopsilia pomona pomona)

Male Lemon Emigrant f-alcmeone puddling at sandbanks

The Lemon Emigrant is a common and very variable butterfly that is found in urban parks and gardens. It is represented by no fewer than seven different 'forms' in Singapore. There are two main groups - the 'crocale' group with the antennae black above, and without silver spots on the underside of the wings; and the 'pomona' forms with the antennae red above and with red-ringed silver spots on the underside of the wings.

Female Lemon Emigrant f-pomona (left) and male Lemon Emigrant f-alcmeone (right)

Female Lemon Emigrant f-crocale

Female Lemon Emigrant f-catilla

This fast-flying species has a strong erratic flight. The colour of the wings range from pale green to orange yellow, with the wing borders on the upperside of the wings varying from a thin black border to wide marginal borders with thick markings. One of the forms - form-catilla is unique in having blood red patches on the underside of both wings that give the butterfly a very different appearance from its other typical forms.

2) The Mottled Emigrant (Catopsilia pyranthe pyranthe)

The Mottled Emigrant is more common than before when its caterpillar host plant, the Seven Golden Candlesticks (Senna alata) became more common as a species that is planted in urban parks and gardens. It can be found in urban parks and gardens where its host plant is found. Another species with a strong erratic flight, the Mottled Emigrant appears whitish in flight and can sometimes be mistaken for another Pieridae.

Male Mottled Emigrant - upperside view of its wings

The wings of the Mottled Emigrant are greenish-white above with a narrow black apical border with a prominent black cell-end spot. The underside is of a slightly darker greenish hue, and numerous reddish-brown striations that gives the underside of the wings a "mottled" look. Females have broader black marginal borders on both wings.

3) The Orange Emigrant (Catopsilia scylla cornelia)

Upperside view of a male Orange Emigrant

The Orange Emigrant has white forewings with black borders and deep orange-yellow hindwings on the upperside. On the underside, both the fore and hindwings are orange-yellow with dark brownish spots and markings. The female has a series of irregular sub-marginal spots on the forewing above and a broad black marginal border on the hindwing. The underside markings of the female are more prominent and the ground colour of the wings is often of a deeper orange than the male.

A female Orange Emigrant trying to oviposit on its host plant, Senna alata

A male Orange Emigrant perches on a leaf of its host plant, Senna alata

Also more regularly found in urban parks and gardens than in the forested nature reserves, the Orange Emigrant with its strong and erratic flight flies amongst the treetops and shrubbery looking for its preferred caterpillar host plants.

Text by Khew SK : Photos by Sunny Chir, Khew SK, Koh CH, Horace Tan and Anthony Wong