eTawau > Insects of Borneo > Caterpillars > A nymphalid at the Tawau River Triangle

Black, spined, and blue in the right light

A butterfly caterpillar in a papaya garden — and a record that stopped short of what it could have been

This is the handsomest caterpillar on this site and the one with the least name attached to it. Velvety black, speckled with white, carrying a row of branched spines whose shafts flare iridescent blue where the light catches them, two broken lines of cream-yellow dashes down the back, and one bright orange-red cone low on each side of every segment.

A velvety black caterpillar on the stem of a low green shrub, seen from above and slightly to one side. Branched spines rise from every segment, black with iridescent blue on the shafts. Two broken rows of short cream-yellow dashes run the length of the back, with scattered small round metallic blue tubercles and fine white speckling between them. A bright orange-red cone sits low on the side of each segment, each carrying a black spine. Four labels mark the branched spines, the metallic blue shafts, the orange-red cone and the paired cream dashes. — **Branched spines on every segment.** That one character settles the family. Papaya garden beside the Tawau River Triangle, 29 July 2007, 3.35 in the afternoon.

The spines make it a butterfly

Look at one spine closely and you see it is not a simple bristle. It has a stout base, a shaft, and short spinelets radiating from the shaft like a bottle brush. A spine built that way is called a scolus, and among Bornean caterpillars it is close to diagnostic for one family: the Nymphalidae, the brush-footed butterflies.

An enlargement of three segments of the same caterpillar. Each branched spine has a stout base, a shaft with an iridescent blue sheen, and short black spinelets radiating from it. Small round metallic blue tubercles sit separately on the body surface between the spines, and an orange-red cone at the base of each lower spine. — **A scolus close up.** The small round blue bumps are separate structures — they are not part of the spines.

So the animal on this page is a butterfly caterpillar, not a moth's. That is worth saying plainly, because most people assume any hairy or spiny caterpillar is a moth. On this site the tussock and the lappet moths are moths; this one is not.

What the photograph will not tell us

The record stops at family, and I am not going to push it further. Two things would settle the genus and neither of them is in the picture.

The head capsule. Its colour, and whether it carries a pair of horns, separates several of the likely genera at a glance. The head is turned away and hidden.
The identity of the shrub. Many nymphalid caterpillars are tied to a single plant family, so a named host plant is often half the identification. What can be seen is opposite, ovate, softly hairy leaves on a soft green stem — and that is as far as it goes.

A snapshot from before the method

This is the earliest record on this site from the Tawau River Triangle, and the photographer is straightforward about what it is:

"Those days I was just a hobby photographer taking snap shots. Only years later I became a field observer, and began to learn to take a series of photos including measuring sizes."

This record is the "before" picture of a working method, and it is kept for exactly that reason. Look at what one snapshot costs, nineteen years later:

One frame instead of a series — so no head, no underside, no second angle.
No scale object — so no size, and this time no arithmetic can recover one.
No photograph of the plant — so half the identification is gone.

Every one of those is now on the checklist used for every record on this site, and this caterpillar is the argument for the checklist. It is not a failed record. It has a date, a place, a camera file and a clear picture of the animal, which is more than most people ever have of anything they have seen. It is simply a record that stopped short — and it stopped short in three specific, avoidable ways.

The papaya garden is still there, ten minutes from the photographer's house, and the shrub may still be growing in it. A single photograph of that plant would finish a nineteen-year-old record, and would very likely carry this animal from family to genus.

Do not handle it. The spines of some nymphalid caterpillars are merely sharp, and some are irritating to the skin — and this one has not been identified, so there is no way to know which. Photograph it and leave it where it is, which is what happened here.

The record

29 July 2007 · 3.35 pm · papaya garden — outside the Triangle

On a low shrub, moving slowly along a stem

Papaya garden beside the Tawau River Triangle, Km 7 Jalan Kuhara, Tawau, Sabah. Across Jalan Kuhara from the Triangle itself, so outside it. One caterpillar, not measured — there was no scale object in the frame and none can be recovered. Velvety black with fine white speckling; two broken rows of short cream-yellow dashes along the back; scattered small round metallic blue tubercles; branched spines (scoli) black with iridescent blue shafts; one orange-red cone low on each side per segment, each carrying a black spine. Head not visible. Lepidoptera: Nymphalidae — a brush-footed butterfly. Subfamily and genus not determined. On an unidentified shrub with opposite, ovate, softly hairy leaves. Moving slowly along a stem. One only. Photographed and returned to the bush; nothing collected. Mosquitoes numerous in the garden.
— iNaturalist observation 401359228

Where this was

The Tawau River Triangle is a block of abandoned fifty-year-old oil palm between the Merotai Road roundabout, Jalan Kuhara and Jalan Utara Baru, at Km 7 of Jalan Kuhara, about 7 km from Tawau town. This caterpillar was outside it, in the papaya garden across the road — the same garden that produced another caterpillar in 2008, a weaver ant queen in 2009 and a tussock moth caterpillar in 2011.

More than half of everything recorded at this locality has come from outside the boundary. Three records inside the Triangle, four in the garden across the road. That is not a weakness in the records — it is the point of them. The garden is not a separate place; it is the edge of this one, and an edge is worth recording as carefully as the middle.

Words you may meet

Nymphalidae: The brush-footed butterflies — the largest butterfly family. The name comes from the adults, whose front pair of legs is reduced to short brushes and not used for walking.
Scolus: (plural scoli) A branched spine on a caterpillar: a stout base carrying a shaft with shorter spines radiating from it. Characteristic of the nymphalids.
Tubercle: A small rounded bump on the body surface. The metallic blue spots on this animal are tubercles, and are separate from the scoli.
Host plant: The plant a caterpillar eats. Many butterflies use only one plant family, so naming the plant often names the butterfly.
Head capsule: The hard, dark head of a caterpillar, distinct from the soft segments behind it. Its colour and any horns are often the quickest way to a genus.

Caterpillars of Borneo — the index this record belongs to
A tussock moth caterpillar — Tawau River Triangle · A hundred lappet moths on a log — Bako — two moths, for comparison with this butterfly
A weaver ant queen with fly larvae · A caterpillar with its bristles in bunches — two more records from the same papaya garden
Tawau River Triangle — the ground this record comes from, and everything else found there
Insects of Borneo

About the photograph. One frame by Wong Fook Yee with a Canon PowerShot A430 at 15:35:34 on Sunday 29 July 2007, f/5.6 at 1/60 s, 5.4 mm, flash fired — fill-flash in afternoon shade, which is why the blue on the spines shows so strongly. It is a camera original that has never been opened in an editor. For this page it has been cropped, brightened and labelled; nothing has been sharpened, recoloured, added or removed. The unmarked full frame is attached to the iNaturalist record above.

The family character — branched scoli — and the account of what would be needed to go further are from the general entomological literature; the locality, the date, the time, the behaviour and the circumstances of the find are the photographer's own field observations, made on one of his Sunday walks. The animal was not measured and the host plant is not identified. All photographs © Wong Fook Yee. Page written 18 September 2026.