Butterfly Biodata:
Genus: Mycalesis Hübner, 1818
Species: perseus Fabricius, 1775
Subspecies: cepheus Butler, 1867
Wingspan of Adult Butterfly: 35-45mm
Caterpillar Local Host Plants: Ischaemum ciliare (Poaceae, common names: Smut Grass), Axonopus compressus (Poaceae, common names: Wide-leaved Carpet Grass, Cow Grass).
Physical Description of Adult Butterfly:
On the upperside, the wings are dark greyish brown with a large but obscure ocellus in space 2 of the forewing. The male has a small, dark brown sex brand in space 1b of the forewing, and another one at vein 7 of the hindwing overlaid with a pale yellow hair tuff. On the underside, both wings are pale brown in ground colour (with the male in darker brown than the female) and have a clear-whitish post-discal band. There is a series of ringed ocelli in the submarginal area on both wings. In the forewing, the submarginal ocelli usually include only one ocellus in each of spaces 2 and 5, and two smaller ocelli in between. In the hindwing, there is a thin, dark indentation line stretching down to (but not beyond) vein 1b. Furthermore, the submarginal series of ocelli has an arched appearance with the ocellus in space 2 moved inwards and out of alignment with those in spaces 1b and 3.
A pair of Dingy Bush Brown. Left: male; Right: female.
Field Observations of Butterfly Behaviour:
The Dingy Bush Brown is a moderately common butterfly in Singapore. Adults can be sighted flying low, in and around grassy patches at several locations across the island. As with other Satyrinae members, the adults fly in an erratic and jerky manner as their wings are closed for a relatively long period during flights.
Early Stages:
Two grass species, Ischaemum ciliare and Axonopus compressus, have been recorded as larval hosts for the Dingy Bush Brown in Singapore so far. The caterpillars feed on leaves of the host plant, and have been observed to forcefully ejecting their frass pellets, a larval habit rarely seen outside the skipper/flat families. They tend to rest lengthwise on the underside of a leaf during pauses between feeds.
Forceful ejection of frass pellets by caterpillars (in all five instars) of the Dingy Bush Brown.
Local host plant #1: Ischaemum ciliare.
Local host plant #2: Axonopus compressus.
A mating pair of the Dingy Bush Brown.Left: male; Right: female.
The eggs are laid singly on the underside of a grass blade. Each oblate ellipsoidal egg (about 1.1mm in diameter and 1mm in height) is pale translucent green. The surface appears smooth to the naked eyes, but is actually sculptured with a polygonal reticulum when viewed with a macro lens.
Two views of an egg of the Dingy Bush Brown .
The egg takes about 3 days to hatch. The young caterpillar nibbles away a portion of the egg shell to exit and then proceeds to devour the rest of the egg shell almost entirely. It has a cylindrical body in whitish colour, and an initial body length of about 3.2mm. The body is covered with dorso-lateral and lateral rows of whitish setae. At the posterior end, there is a pair of backward-pointing processes. Its dark colored head features a number of setae and has a pair of short and rounded horns and a few lateral protuberances.
Two views of a newly hatched caterpillar, length: 3.25mm.
As a result of its leaf diet, the 1st instar caterpillar soon takes on a greenish undertone and its body lengthens gradually. The first instar lasts about 2.5-3 days with the body length increases to about 6-6.5mm.
Two views of a 1st instar caterpillar, length: 6mm.
Two views of a late 1st instar caterpillar, dormant prior to its moult, length: 6.25mm.
In the 2nd instar, the cephalic horns become pointed and the two anal processes longer and thus pronounced. The few lateral conical protuberances on the head capsule are now much smaller and whitish in colour. The body is yellowish green. The head and body is also adorned with numerous minute tubercles, each with a single seta emanating from it. The 2nd instar lasts about 2.5-3 days with the body length reaches about 10-10.5mm.
Two views of a 2nd instar caterpillar, early in this stage, length: 6.8mm.
Two views of a 2nd instar caterpillar, length: 8.5mm.
Two views of a late 2nd instar caterpillar, dormant prior to its moult, length: 10mm.
The 3rd instar caterpillar mostly resembles the previous instar. The head capsule is reddishbrown in the cephalic horns and the basal areas around the mouth parts but yellowish brown elsewhere. This stage also takes 2.5-3 days to complete with body length reaching about 14.5-15mm.
Two views of 3nd instar caterpillar, early in this stage, length: 10.2mm.
Two views of a 3nd instar caterpillar, length: 15mm.
Two views of a late 3nd instar caterpillar, dormant prior to its moult, length: 14.5mm.
The 4th instar caterpillar bears a close resemblance to the 3rd instar caterpillar with no obvious change of any features or markings. The 4th instar lasts about 4 days with body length reaching about 20-22mm.
Two views of a newly moulted 4th instar caterpillar, length: 14mm.
Two views of a 4th instar caterpillar, late in this stage, length: 20mm.
Two views of a late 4th instar caterpillar, dormant prior to its moult, length: 22mm.
The next moult brings the caterpillar to its 5th and final instar. Now the caterpillar could appear in two colour forms: a brown form which is mostly pale brown and a green form which is pale yellowish green. In a period of about 6 days, the body grows to a maximum length of about 40-41mm.
Two views of a newly moulted 5th instar caterpillar, green form, length: 19mm.
Two views of a 5th instar caterpillar, green form, length: 32mm.
Toward the end of the 5th instar, the body gradually shrinks in length. Typically, the caterpillar will seek out a spot on the underside of a leaf blade to spin a silk pad. It then anchors itself there via its anal end, and assumes its upside-down pre-pupatory pose.
Two views of a 5th instar caterpillar, brown form, late in this stage, length: 33.5mm.
A prep-pupa of the Dingy Bush Brown.
After one day as a pre-pupa, pupation takes place. The smooth pupa is mostly green throughout with its surface dotted with numerous tiny whitish spots. It is somewhat angular in appearance, with a small dorsal keel on the thorax and ridges defining the dorsal wing margins. There are a few small black spots dotting the wing pad margin. Dorso-lateral pairs of round and whitish spots can be observed on some abdominal segments. Length of pupae: 14-15mm.
Three views of a pupa of the Dingy Bush Brown.
After about 5 days of development, the pupa becomes darkened in color, and the ringed-spot on the forewings can now be seen through the pupal skin in the wing pads. The next day the eclosion event takes place with the adult butterfly emerges to start the next phase of its life cycle.
Three views of a mature pupa of the Dingy Bush Brown.
A newly eclosed female Dingy Bush Brown.
References:
Genus: Mycalesis Hübner, 1818
Species: perseus Fabricius, 1775
Subspecies: cepheus Butler, 1867
Wingspan of Adult Butterfly: 35-45mm
Caterpillar Local Host Plants: Ischaemum ciliare (Poaceae, common names: Smut Grass), Axonopus compressus (Poaceae, common names: Wide-leaved Carpet Grass, Cow Grass).
Physical Description of Adult Butterfly:
On the upperside, the wings are dark greyish brown with a large but obscure ocellus in space 2 of the forewing. The male has a small, dark brown sex brand in space 1b of the forewing, and another one at vein 7 of the hindwing overlaid with a pale yellow hair tuff. On the underside, both wings are pale brown in ground colour (with the male in darker brown than the female) and have a clear-whitish post-discal band. There is a series of ringed ocelli in the submarginal area on both wings. In the forewing, the submarginal ocelli usually include only one ocellus in each of spaces 2 and 5, and two smaller ocelli in between. In the hindwing, there is a thin, dark indentation line stretching down to (but not beyond) vein 1b. Furthermore, the submarginal series of ocelli has an arched appearance with the ocellus in space 2 moved inwards and out of alignment with those in spaces 1b and 3.
Field Observations of Butterfly Behaviour:
The Dingy Bush Brown is a moderately common butterfly in Singapore. Adults can be sighted flying low, in and around grassy patches at several locations across the island. As with other Satyrinae members, the adults fly in an erratic and jerky manner as their wings are closed for a relatively long period during flights.
Early Stages:
Two grass species, Ischaemum ciliare and Axonopus compressus, have been recorded as larval hosts for the Dingy Bush Brown in Singapore so far. The caterpillars feed on leaves of the host plant, and have been observed to forcefully ejecting their frass pellets, a larval habit rarely seen outside the skipper/flat families. They tend to rest lengthwise on the underside of a leaf during pauses between feeds.
Forceful ejection of frass pellets by caterpillars (in all five instars) of the Dingy Bush Brown.
The eggs are laid singly on the underside of a grass blade. Each oblate ellipsoidal egg (about 1.1mm in diameter and 1mm in height) is pale translucent green. The surface appears smooth to the naked eyes, but is actually sculptured with a polygonal reticulum when viewed with a macro lens.
The egg takes about 3 days to hatch. The young caterpillar nibbles away a portion of the egg shell to exit and then proceeds to devour the rest of the egg shell almost entirely. It has a cylindrical body in whitish colour, and an initial body length of about 3.2mm. The body is covered with dorso-lateral and lateral rows of whitish setae. At the posterior end, there is a pair of backward-pointing processes. Its dark colored head features a number of setae and has a pair of short and rounded horns and a few lateral protuberances.
As a result of its leaf diet, the 1st instar caterpillar soon takes on a greenish undertone and its body lengthens gradually. The first instar lasts about 2.5-3 days with the body length increases to about 6-6.5mm.
In the 2nd instar, the cephalic horns become pointed and the two anal processes longer and thus pronounced. The few lateral conical protuberances on the head capsule are now much smaller and whitish in colour. The body is yellowish green. The head and body is also adorned with numerous minute tubercles, each with a single seta emanating from it. The 2nd instar lasts about 2.5-3 days with the body length reaches about 10-10.5mm.
The 3rd instar caterpillar mostly resembles the previous instar. The head capsule is reddishbrown in the cephalic horns and the basal areas around the mouth parts but yellowish brown elsewhere. This stage also takes 2.5-3 days to complete with body length reaching about 14.5-15mm.
The 4th instar caterpillar bears a close resemblance to the 3rd instar caterpillar with no obvious change of any features or markings. The 4th instar lasts about 4 days with body length reaching about 20-22mm.
The next moult brings the caterpillar to its 5th and final instar. Now the caterpillar could appear in two colour forms: a brown form which is mostly pale brown and a green form which is pale yellowish green. In a period of about 6 days, the body grows to a maximum length of about 40-41mm.
Toward the end of the 5th instar, the body gradually shrinks in length. Typically, the caterpillar will seek out a spot on the underside of a leaf blade to spin a silk pad. It then anchors itself there via its anal end, and assumes its upside-down pre-pupatory pose.
After one day as a pre-pupa, pupation takes place. The smooth pupa is mostly green throughout with its surface dotted with numerous tiny whitish spots. It is somewhat angular in appearance, with a small dorsal keel on the thorax and ridges defining the dorsal wing margins. There are a few small black spots dotting the wing pad margin. Dorso-lateral pairs of round and whitish spots can be observed on some abdominal segments. Length of pupae: 14-15mm.
After about 5 days of development, the pupa becomes darkened in color, and the ringed-spot on the forewings can now be seen through the pupal skin in the wing pads. The next day the eclosion event takes place with the adult butterfly emerges to start the next phase of its life cycle.
References:
- [C&P4] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society.
- Butterflies of Thailand, Pisuth Ek-Amnuay, 2nd Edition, 2012.
- A Field Guide to the Butterflies of Singapore, Khew S.K., Ink On Paper Communications, 2010.
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