Butterfly of the Month - December 2024

Butterfly of the Month - December 2024

The Felder's Royal (Tajuria mantra mantra)

2024 is almost over, as Christmas has come and gone, and many residents of Singapore are making their way back to this little Red Dot after a good vacation abroad. As with most Decembers (except during Covid period), it is a time for locals to get away for a good break from work or school. The local weather has not been cooperative for butterfly outings, as this is also the period of the NorthEast monsoons where the region gets inundated with heavy rains.

As it was, there were flash floods just yesterday in Singapore, as torrential rains descended on the island with a vengeance. Despite careful planning, constant upgrading and drainage expansion works, the local agency, Public Utilities Board still has to contend with flooding (not ponding!) in Singapore from time to time. Several low-lying areas will continue to see these occasional flash floods due to the much larger volumes of water coming down in a much shorter time compared to yesteryears.

Globally, the world waits to see how the new Trump Administration in the US will craft their new policies that will affect bilateral politics, economies and world security when the new President of the United States of America is sworn in in early January 2025. Will the new world order be more peaceful for everyone where there is mutual economic growth and stability? Or will the world be divided between the superpowers? 2025 will be a watershed year for global politics.

And as if to remind us that life is fragile, where we, or our loved ones can be taken away in a flash, there were two aircraft disasters in the past week ending 2024 tragically for some passengers and their families. The first, an Azerbaijan plane carrying almost 70 passengers crashed in Kazakhstan, allegedly shot down by the Russians. There were 27 survivors. Then another tragic crash happened at Muan International Airport in Korea, where a plane carrying 181 passengers and crew smashed into a concrete barrier after an emergency landing. Two crew members survived.

Our final Butterfly of the Month for 2024 is the Felder's Royal (Tajuria mantra mantra). This species was re-discovered in Singapore in 1999. It is relatively uncommon but widely distributed across Singapore. Sightings of the Felder's Royal have been recorded from urban parks and gardens as well as the forested nature reserves. Around noon, the fast-flying adults have been sighted taking nectar at flowering plants in both hill parks and in gardens sited along the fringe of nature reserves. At times several adults could be seen dog-fighting at tree-top level in the mid afternoon.

The upperside of the male is shining greenish-blue and the female is paler purplish blue. Both sexes have a broad apical black border in the forewing, and a black costal border in the hindwing with inner edges evenly curved to below vein 6 in male and to vein 4 in female. The female has additional marginal spots at tornus and in spaces 1b, 2 to 4.

On the underside, both sexes are drab greyish-brown. The forewing post-discal line is much closer to termen than to the cell-end. The hindwing has large black tornal spots in spaces 1a and 2 which are broadly orange-crowned. There are two pairs of white-tipped tails at ends of veins 1b and 2 respectively. The species is often confused with the Flash Royal (Tajuria deudorix ingeni) that was recently re-discovered in 2023 after its life history was documented. Key differences between the two species can be found in the blog post.

The Felder's Royal's caterpillars, thus far, feed exclusively on one species of mistletoe, Macrosolen cochinchinensis (Common Chinese Mistletoe) in Singapore. Many of the Lycaenidae's caterpillars depend on these parasitic and hemiparasitic plants and this underlines the importance of these often "unwelcomed" plants in our environment. Without these parasitic caterpillar host plants, their respective butterfly species will go extinct.

Text by Khew SK : Photos by Ash Foo, Choy CW, Khew SK, Koh CH, Loh MY, Low JK, Michael Soh, Horace Tan, Bene Tay and Anthony Wong.

Life History of the Forget-me-not

Life History of the Forget-Me-Not (Catochrysops strabo strabo)

Butterfly Biodata:
Genus: Catochrysops Boisduval, 1832
Species: strabo Fabricius, 1793
Subspecies:strabo Fabricius, 1793
Wingspan of Adult Butterfly: 15-17mm
Caterpillar Local Host Plants: Grona heterocarpos (Fabaceae, common name: Asian Tick Trefoil), Dendrolobium umbellatum (Fabaceae, common names: Dendulang, Petai Belalang, Petai Laut, Sea Dendrolobium, 伞花假木豆).

The upperside of a male Forget-me-not.

A male Forget-me-not puddling on wet ground.

Physical Description of Adult Butterfly:
On the upperside, the male is pale purplish blue with a black marginal spot in space 2 of the hindwing; the female is pale bluish with broad black apical area on the forewing and has an orange-crowned black spot in space 2 of the hindwing. On the underside, both sexes are pale buff with the usual streaks and spots. In the hindwing, there is a long filamentous white-tipped black tail at vein 2 and an orange-crowned black spot in space 2. In the forewing, there is a small costal spot which is placed midway between the cell spot and post-discal streak.

The upperside of a female Forget-me-not.

A Forget-me-not perching on a developing inflorescence of Grona heterocarpos.

A female Forget-me-not perching on a leaf of Dendrolobium umbellatum in Chinese Garden. Note the protruding ovipositor.

Field Observations:
The Forget-me-not is moderately rare in Singapore. In the past, the adults were infrequently found in open wastelands. However, with the widespread planting in recent years of its alternative host plant, Dendrolobium umbellatum, adults sightings have become more frequent in the last few years. The adults fly with an erratic flight, and have been sighted taking nectar at flowering plants. Both sexes have been observed to sunbathe with partly or fully opened wings in sunlit spots. Males also have a habit of puddling on damp footpaths and wet grounds.

A male Forget-me-not taking nectar from a flower of Tridax procumbens (Coat Buttons).

A sunbathing female Forget-me-not giving us a view of its upperside.

A male Forget-me-not perching one a leaf of Grona heterocarpos in a wasteland.

Early Stages:


A video clip showing various stages of the life cycle of the Grey Tinsel.

In Singapore, thus far only two larval host plants, both from the Fabaceae family, have been identified. One of them is Grona heterocarpos, a relatively rare shrub found in open wastelands. The other plant is Dendrolobium umbellatum, a shrub or small tree usually found along seashores and in beach forests, but widespread cultivation of this plant in the past decade has made it a common sight in various gardens, parks and other urban settings. On the host plants, the early stages of the Forget-me-not feed on the flower buds, flowers and developing fruits, with a strong preference for flower buds. The caterpillars of the Forget-me-not have a facultative myrmecophilous relationship with ants, and have been observed to be attended by at least two ant species in the field.

Local host plant #1: Grona heterocarpos (Fabaceae, common name: Asian Tick Trefoil).

Local host plant #2: Dendrolobium umbellatum (Fabaceae, common names: Dendulang, Petai Belalang, Petai Laut, Sea Dendrolobium, 伞花假木豆).

Close-up views of the inflorescene/flowers of the host plant. Left: Grona heterocarpos. Right: Local host plant #2:Dendrolobium umbellatum.

A mating pair of Forget-me-not found in a wasteland in the west.

Eggs are laid singly in space between bracts of flower buds or between developing leaflets of the host plant, and are concealed within a layer of transparent membrane. At times, the egg might be exposed as a result of further growth of flower buds and leaflets. Each bun-shaped egg is about 0.5mm in diameter and pale greenish in color. It is bun-shaped with a surface reticulated with rather small depressions.

A tattered Forget-me-not female laying an egg on a developing inflorescence of Grona heterocarpos.

Two views of a freshly laid egg of the Forget-me-not on the flower buds of Grona heterocarpos.

Two close-up views of an egg of the Forget-me-not.

Left: A fully developed egg. Right: empty egg shell left behind by the newly hatched caterpillar.

It takes about 2-3 days for the egg to hatch. The young caterpillar consumes just enough of the egg shell to emerge. It is pale yellowish brown, and has a length of about 0.9mm. Long setae (hairs) run along the length of the body dorsally as well as sub-spiracularly. The head capsule is dark brown to black in colour. The 1st instar lasts about 2 days with the body length increased to about 1.8mm.

Two views of an early 1st instar caterpillar of the Forget-me-now, length: 1mm.

Two views of a 1st instar caterpillar of the Forget-me-not feeding on a flower bud of Dendrolobium umbellatum, length: 1.7mm.

A late 1st instar caterpillar of the Forget-me-not, dormant prior to the moult to the next instar.

In the 2nd instar caterpillar, in addition to the long setae running along the length of the body dorsally and sub-spiracularly, numerous short setae cover the body surface. The body base colour is pale yellowish brown. Pale whitish dorsal and dorso-lateral streaks gradually become distinguishable as the second instar progresses. Sub-spiracularly, the body rim is pale whitish. The head capsule remains dark brown to black in color, and will remain so in the next instar. The 2nd instar lasts for about 2-3 days, with the body length reaching up to 2.8-3.0mm.

Two views of an early 2nd instar caterpillar of the Forget-me-not, length: 2mm.

Two views of a 2nd instar caterpillar of the Forget-me-not, length: 2.5mm.

Two 2nd instar caterpillars of the Forget-me-not feeding on a developing inflorescence of Grona heterocarpos.

Two views of a 2nd instar caterpillar, late in this stage, dormant prior to its moult.

In the 3rd instar, the dorsal and sub-spiracular setae appears to be proportionately shorter compared to those in the previous instar. The body is now covered in a dense coat of whitish stellate setae, and the pale whitish dorsal and sub-spiracular bands are more prominent. From the outer sides of the dorsal bands, short dorsal-lateral streaks emanate outwards, giving an appearance of multiple chevron markings. The body base color ranges from pale yellow green to pale yellowish brown. The dorsal nectary organ on the 7th abdominal segment is present and barely discernible. As the body grows to a length of around 5.5mm, the caterpillar stops feeding and comes to rest at a spot on the underside of a leave or stem to prepare for the next moult. After about 3 days in the 3rd instar, the moult to the 4th and final instar takes place.

Two views of an early 3rd instar caterpillar of the Forget-me-not feeding on a developing inflorescence of Grona heterocarpos, length: 3mm.

Two views of a 3rd instar caterpillar of the Forget-me-not, length: 5mm.

Two views of a late 3rd instar caterpillar of the Forget-me-not, dormant prior to its moult to the final instar.

The 4th instar caterpillar resembles the 3rd instar caterpillar in most body features/markings, but with greater contrasting whitish chevron markings and sub-spiracular band. The head capsule is now pale orange brown. The caterpillar in this final instar can appear in the two color forms. In the green form, the body base colour is predominantly green, and in the red form, the body base colour is yellowish brown, the central dorsal band is reddish brown and there are reddish brown streaks/patches flanking the dorsal chevron markings. The dorsal nectary organ on the dorsum of the 7th abdomina segment is now easily discernible, and so is the pair of tentacular organs on the 8th abdominal segment.

Two views of an early 4th instar caterpillar of the Forget-me-not, green form.

Caterpillars of the Forget-me-not, one red form and one green form, feeding on a developing inflorescence of Grona heterocarpos.

Two views of a 4th instar caterpillar of the Forget-me-not on Dendrolobium umbellatum, green form, length: 6.5mm.

Caterpillars of the Forget-me-not, in both colour forms, feeding on an inflorescence of Grona heterocarpos.

Two views of a 4th instar caterpillar of the Forget-me-not, red form, length: 10mm.

Two views of a 4th instar caterpillar of the Forget-me-not, green form, length: 10mm.

A 4th instar caterpillar of the Forget-me-not found in the field with ants in attendance.

Two views of a 4th instar caterpillar of the Forget-me-not on Dendrolobium umbellatum, green form, length: 9.5mm.

The final instar lasts about 3.5-4 days with the body length reaching up to 11mm. On the last day of the 4th instar, the body colour of caterpillar decolorises to pale pinkish brown or pale green with a pink tone. The caterpillar ceases its feeding activity and begin to wander around to select its pupation site.

A late 4th instar caterpillar of the Forget-me-not found in the field with ants in attendance.

Two views of a late 4th instar caterpillar, red form.

Two views of a late 4th instar caterpillar, green form.

As the caterpillar enters the pre-pupatory phase of its life cycle, its body gradually shrinks in length. The pre-pupatory caterpillar typically settles for a spot on a surface which is partially concealed either among foliage of the host plant or in leaf litter. At the chosen pupation site, it spins a silk girdle and a silk pad to which it attaches with claspers at its posterior end.

Two views of a pre-pupa of the Forget-me-not, red form.

Two views of a pre-pupa of the Forget-me-not, green form.

After about 1 day of the immobile pre-pupatory stage, pupation takes place. The pupa is held firmly via its cremaster to the silk pad. It is 8 to 9mm in length, with the typical shape for a lycaenid pupa. The fresh pupa is either yellow green or pale beige brown, but it will eventually turn pale yellowish to beige brown within first day. The pupa is adorned with multiple small black markings of varying sizes and shapes.

Two views of a pupa of the Forget-me-not, length: 8.5mm.

About four to five days later, the pupa becomes darkened in color signaling the imminent emergence of the adult. One can now tell the gender of the soon-to-emerge adult stage from the coloration of the wing pad at this stage (see pictures below). The next day the adult Forget-me-not emerges from the mature pupa. Total pupal period is 5 or 6 days.

Two views of a mature pupa of a female Forget-me-not.

Two views of a mature pupa of a male Forget-me-not.


A male Forget-me-not emerging from its chrysalis.

A newly eclosed male Forget-me-not resting on its pupal case.

A newly eclosed female Forget-me-not resting next to its pupal case.

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.

Text by Horace Tan; Photos by Jonathan Soong, Koh Cher Hern, Khew SK and Horace Tan.