Butterfly Biodata:
Genus: Rapala Moore, 1881
Species: Species: dieneces Hewitson, 1878
Sub-species: dieneces Hewitson, 1878
Wingspan of Adult Butterfly: 15-18mm
Caterpillar Local Host Plants: Bridelia tomentosa (Phyllanthaceae, common name: Pop-gun Seed, 土蜜树), Prunus polystachya (Rosaceae), Trema tomentosa (Ulmaceae, common name: Rough Trema, Poison Peach), Mallotus paniculatus (Euphorbiaceae, common name: Turn-in-Wind), Ixora sp. (Rubiaceae), Syzygium sp. (Myrtaceae).
Physical Description of Adult Butterfly:
On the upperside, the female is entirely brown whereas the male is deep red with broad black border on the forewing, while the hindwing is shaded with black at the cell area and tornal margin. As with other Rapala spp., the male has an oval-shaped brand in space 7 on the hindwing. On the underside, both sexes are ochreous or pale brown. The markings are typical for Rapala spp, with cell-end bars on both wings, and narrow brown postdiscal band edged with white on the side nearer to the termen. The hindwing carries a white-tipped filamentous tail at the end of vein 2 with a tornal lobe between veins 1a and 1b. In addition, there is a black tornal spot, a bluish green patch in space 1b, an orange-crowned black sub-marginal spot in space 2, and black post-discal striae in spaces 1b and 2.
Field Observations:
The Scarlet Flash is moderately rare in Singapore. It is mainly found in the forested areas of the nature reserves. The adults are fast flyers and take rapid flights among foliage at the forest edges. At times, adults come at rest on flowers for their nectary intakes.
Early Stages:
The Scarlet Flash is polyphagous as its early stages feed on a number of host plants from different families. Locally six plants, Bridelia tomentosa, Prunus polystachya, Trema tomentosa, Mallotus paniculatus, a Syzygium sp. and an Ixora sp., have so far been identified as the larval hosts. The caterpillars of the Scarlet Flash feed on the flowers, flower buds, young and tender leaves of the host plants. In the wild, the caterpillars are typically found in the company of small black ants.
Eggs are laid singly on a leaf, a part of an inflorescence or a flower of the host plant. Each egg is about 0.5-0.6mm in diameter, greenish in colour when freshly laid. It is bun-shaped with a depressed micropylar at the pole and a surface reticulated with very fine ridges.
It takes about 3 days for the egg to hatch. The newly hatched is pale yellowish with moderately long dorsal and lateral setae. Its body has a length of about 1.2mm. Pale reddish brown patches can be seen on the 1st, 6th-8th abdominal segments and on the anal plate. It also has a black prothoracic shield and a black head. As it feeds and grows in this instar, the brownish patches darkened gradually. After about 3 days of growth in the first instar, and reaching a length of about 2.2mm, the caterpillar moults to the next instar.
The 2nd instar caterpillar is pale yellowish brown in base color and has dark reddish brown patches on the thoracic segments, as well as in the 1st, 6th-8th abdominal segments. There are also two brown spots on the anal plate. From above, the 7th to 10th segments appear to have fused together to form a saucer-like structure. The dorsal nectary organ on the 7th abdominal segment is now discernible. There are short black setae emanating from rows of conical projections occurring dorso-laterally. Numerous pale yellowish short setae occur sub-spiracularly along the body fringe. The 2nd instar caterpillar reaches a length of about 4mm, and after about 3 days in this stage, it moults again.
The 3rd instar caterpillar resembles the 2nd instar caterpillar closely, but with the hair-like setae replaced by paddle-like setae. These paddle-like setae are brown to black for those occurring dorso-laterally and on the posterior segments, while remaining ones along the body fringe are pale yellowish brown. On the 7th abdominal segment, the dorsal nectary organ is now more readily observed. The 3rd instar takes about 3 days to complete with the body length reaching about 8mm before the next moult.
The 4th instar caterpillar has a more striking appearance, featuring broad yellowish green or pale yellowish brown dorsal band on the 2nd to 5th abdominal segment, and brown to dark brown lateral patches on almost all body segments. Tentacular organs on the 8th abdominal segments can now be easily observed being everted from time to time. The 4th instar takes about 4 days to complete with the body length reaching up to 14mm.
The 5th instar caterpillar has similar markings as in the 4th instar with more contrasting coloration between the yellowish to greenish dorsal band on the middle segments and reddish brown to dark brown markings on the other body segments. It is not uncommon to see numerous ants attending to a 5th instar caterpillar in field observations.
After about 5-6 days of feeding and reaching a length of about 20-21mm, the caterpillar stops food intake and wanders around for a pupation site. During this time, its body gradually shortened and body color darkens. Typically the caterpillar chooses a concealed space in a leaf litter for its pupation site.
The pre-pupatory caterpillar prepares for pupation by spinning a silk girdle and a silk pad to which it attaches itself via anal claspers. After about 1 day as a pre-pupa, pupation takes place. The pupa has a shape typical of most lycaenid species with a length of 11-12.5mm. It is pale reddish to yellowish brown in base colour, and its surface bears numerous small dark speckles.
Eight to nine days later, the pupa darkens, first in the wing pad and thorax, then progressively in the abdomen. The presence and absence of the reddish patch in the wing pads gives an early indication of the sex of the soon-to-emerge adult. The next day, the pupal stage comes to an end with the emergence of the adult butterfly.
References:
- [C&P5] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, G. and N. van der Poorten (Eds.), 5th Edition, Malayan Nature Society, 2020.
- Butterflies of Thailand, Pisuth Ek-Amnuay, 2nd Edition, 2012.
- A Field Guide to the Butterflies of Singapore, Khew S.K., Ink On Paper Communications, 2nd Edition, 2015.
