The Singapore Four Line Blue (Nacaduba pavana singapura)
A couple more hours, and August 2024 will come to an end. August is the month when Singapore celebrates its National Day. Every year since this 'little red dot's' independence from Malaysia in 1965, Singaporeans of all walks of life come together to watch the parade at various designated locations in Singapore. It is a day of celebrations and pride as Singaporeans and residents wish the nation a happy birthday.
This year, 2024, Singapore celebrated its 59th year of independence. It was also a special year that marked the appointment of Singapore's fourth prime minister - Mr Lawrence Wong, who took over from former PM Lee Hsien Loong, who was prime minister from 2004 - 2024. It was also the first year that PM Lawrence Wong shared his vision for Singapore in his inaugural National Day Rally.
A Singapore Four Line Blue feeding on the flower of the Red Bush (Leea rubra)
It is therefore apt that, as a nation celebrates its 59th birthday, that we feature a small butterfly that carries the word 'singapura' in its taxonomic name - the Singapore Four Line Blue (Nacaduba pavana singapura). This small Lycaenidae that carries the subspecies name referring to Singapore, is one of the members of the 4-line blues of the genus Nacaduba.
The Singapore Four Line Blue has been described as "with a pale greyish blue male, and is seldom seen except in Singapore, where it is sometimes quite common on the landward edge of mangrove swamps."Indeed this is the case, where the species is a regular at the Sg Buloh Wetland Reserve (SBWR), Kranji Nature Trail and Mandai Mangroves where its caterpillar host plants Derris trifoliata (Leguminosae), Andira inermis (Leguminosae), Allophylus cobbe (Sapindaceae) grow quite commonly.
A female Singapore Four Line Blue with partially opened wings showing the uppersides of the wings
The butterfly is rather small, with a wingspan of usually less than 20mm. Above, the male is greyish blue with a thread-thin border; the female is brown with a pale blue discal patch on the forewing and blue dusting on the basal part of the hindwing. The species belongs to the pavana group of the genus - a primary characteristic being the lack of a pair of sub-basal lines on the underside of the forewing.
Underneath, both sexes are greyish brown with the bands composed of a double series of whitish striae inwardly lined with darker lines with the space between them appear to be paler than the ground colour. On each hindwing, there is an orange-crowned tornal spot lightly speckled with bluish-green metalic scaling. Next to the tornal spot, a pair of filamentous white-tipped tails occurs at end of vein 2. Marginal and submarginal spots are black and stand out against the ground colour of greyish brown.
The Singapore Four Line Blue is skittish and flies erratically as it searches for food or, in the case of the female, is looking for its caterpillar host plants to oviposit. It is alert and is difficult to photograph in the field due to its small size and erratic flight. However, when it is busy ovipositing or occasionally stopping to feed at flowering plants, it gives a fair chance for a determined butterfly photographer to get a good shot of it.
A female Singapore Four Line Blue ovipositing.
A Singapore Four Line Blue feeding on the flower of the Pig's Grass (Synedrella nodiflora)
Males of the Singapore Four Line Blue are seldom seen to puddle, like several of its other cousins in the genus Nacaduba. They are more often spotted feeding at flowers like the females. The complete life history of the Singapore Four Line Blue has been successfully recorded in Singapore, and is recorded here on this blog. The caterpillars are polyphagous and feed on at least three different host plants usually found growing in back-mangrove habitats.
Text by Khew SK : Photos by Federick Ho, Khew SK, Low JK, Ong LM, Horace Tan and Angela Yeo.
