The Swallowtails generically refer to the family Papilionidae, which includes large butterflies and some of the most magnificent and majestic butterflies in the tropics. Although usually referred to as the "Swallowtails", many of the Malaysian and Singaporean species are tailless.
This article features the Papilionidae which are true "swallowtails" in that these species possess spatulate tails on the hindwings. All the five species of Swallowtails found in Singapore are large butterflies, predominantly black and prominently marked with white, red and blue.
The Swallowtail species are strong on the wing, except when feeding or ovipositing, and can take to the wing very ably if disturbed. A peculiarity of the flight of the Swallowtails is that the forewings flutter rapidly whilst the hindwings are kept fairly still - usually when feeding.
The host plants of the Swallowtails include several species of Rutaceae (e.g. Citrus, Murraya, Zanthocylum and Luvunga) and Aristolochiacea (A. acuminata, A. ringens and A. foveolata). Of the five species of Swallowtails found in Singapore, one belongs to the genus Pachliopta and the other four belong to the genus Papilio. All the species have jet black opaque eyes and robust clubbed antennae.
The five Swallowtail species found in Singapore are :
- Common Mormon (Papilio polytes romulus)
- Blue Helen (Papilio prexaspes prexaspes)
- Great Helen (Papilio iswara iswara)
- Banded Swallowtail (Papilio demolion demolion)
- Common Rose (Pachliopta aristolochiae asteris)
The Common Mormon is probably the most abundant of the Swallowtails and is both an urban and a forest butterfly in Singapore. In urban areas, where its preferred host plant, Indian Curry Leaf (Murraya koenigii) is cultivated, the species is often seen ovipositing on the pungent leaves of the host plant. In forested areas, the caterpillars are usually found on the jungle relative of the Murraya. When the preferred host plant is not available, the caterpillars are sometimes found on various species of Citrus as well - most commonly on the Pomelo.
The male Common Mormon is predominantly black with a series of pale white spots running along the hindwing forming a band, with a few small spots along the margin of the forewings, creating a continuation of the hindwing band. On the hindwing, the underside has a series of red submarginal lunules.
The female is polymorphic in Malaysia and Singapore, with the form-cyrus resembling the male but has a red tornal spot in space 1a on the upperside of the hindwing. The female form-polytes resembles the Common Rose (Pachliopta aristolochiae asteris) but her black abdomen (as opposed to the Common Rose's red abdomen) instantly gives her away.
The Blue Helen (Papilio prexaspes prexaspes)
The Blue Helen is essentially a forest butterfly and is rarely seen in urban areas, preferring the sanctuary of Singapore's nature reserves. It is the rarest of the Swallowtail species in Singapore, and most often observed puddling along muddy footpaths in the nature reserves. Also a predominantly black butterfly, the Blue Helen has a white discal patch on the hindwings formed by large white spots. The underside hindwing feature a series of bluish grey spots towards the tornal area.
The species is swift on the wing and erratic in flight. The wings are more robust than the Common Mormon, and the spatulate tails are large and thick. Females are sometimes seen visiting flowers in the forested areas.
The Great Helen (Papilio iswara iswara)
The Great Helen is the largest amongst the Swallowtails found in Singapore. With a wingspan often exceeding 160mm, it is a spectacular butterfly when seen in flight. Like its closely related cousin, the Blue Helen, the Great Helen is also a forest butterfly, and remains mainly in the nature reserves, flying high amongst the treetops visiting the flowers of the trees like the Saraca and Syzygium spp. Occasionally, it descends to feed on low garden flowering bushes like the Ixora which are planted at reservoir parks fringing the nature reserves.
The large white patch on the hindwings extends from vein 4 to the apex and on the underside, there are blue lunules with large black-centred red ocellus at the tornal area. In the female, there is a pair of black-centred ocelli on the upperside of the hindwings at spaces 1a and 2.
When the Great Helen stops to rest, the forewings cover the most of the white patches on the hindwings, appearing totally black. It rests with wings opened flat on large leaves. When disturbed, it takes flight and there is a flash of white as the patches on the hindwings are revealed. It is believed that the momentary distraction of the white patches would surprise a predator for a split second, whilst the butterfly makes a hasty escape.
In Singapore, the Great Helen does not appear to puddle at damp streams like its cousins the Red Helen (Papilio helenus helenus) - found in Malaysia, and the Blue Helen.
The Banded Swallowtail (Papilio demolion demolion)
The Banded Swallowtail is another swift flying Swallowtail, often seen flying erratically amongst the forested areas in Singapore's nature reserves. Although sometimes seen in suburban gardens, the species still prefers to remain close to the sanctuary of the forested areas. The wings are black with a pale greenish macular band extending from the apex of the forewing to the mid-dorsum of the hindwing. The hindwing has a series of pale greenish lunulate submarginal spots and a black ocellus ringed with orange red at the tornus.
The spatulate tails are narrower and longer than the other Swallowtail species found in Singapore. The underside markings are paler and there is a series of attractive patterns on the hindwings with orange spots at the tornal and costal area.
The early stages of this species are unique in the sense that it is one of the very few species of butterflies which lays its eggs on top of each other, forming a rod protruding from a leaf of the host plant. The caterpillars are gregarious and feed together in the first four instars.
The Common Rose (Pachliopta aristolochiae asteris)
The Common Rose is a pretty Swallowtail, with its reddish pink spots and abdomen. The predominantly black forewings are shaded with grey along the distal half. The underside has a white post-discal patch and the series of reddish pink submarginal spots. The sexes are similar except for the rounder wing contours of the female.
The caterpillars of the Common Rose feeds on a variety of Aristolochia and it has been successfully bred on A. acuminata, A. ringens and A. foveolata. It is believed that it also feeds on Thottea sp as well.
The bright colours of the species is a warning to predators that it is distasteful. The female of the related Common Mormon (form-polytes) mimics the Common Rose for protection. In Singapore, the species can most often be found at the Singapore Botanic Gardens, Alexandra Hospital Butterfly Trail and the Singapore Zoological Gardens at Mandai, where its host plants are found.
Recently, the presence of what is believed to be a different subspecies of the Common Rose has been observed with regularity. This subspecies has totally black hindwings where the typical white patch of the subspecies asteris is missing. It is believed that this is the subspecies antiphus which is of Bornean origin. How this subspecies appeared in Singapore is a mystery. It could be that it was inadvertently imported with some plants or perhaps a gravid female accidentally escaped from the butterfly park at Sentosa and established a colony here in Singapore. No one can be certain of how it came to Singapore, but it is now quite regularly observed in Singapore.
There is a sixth "Swallowtail" which may occur in Singapore and this is the female form-distantianus of the Great Mormon (Papilio memnon agenor). The shot shown here, courtesy of Leslie Day of ButterflyCircle, was taken at Koh Samui in Thailand. This form of the female can also be found in Malaysia, and hence it should be looked for in Singapore. Though the predominant female forms in Singapore are form-esperi, form-butlerianus and form-agenor, this Swallowtail female form-distantianus has thus far not been reliably sighted nor photographed yet.
Text by Khew SK : Photos by Khew SK, Sunny Chir, Tan CP, Federick Ho, James Chia and Leslie Day