11 September 2010

The Life History of the Long Banded Silverline

Life History of the Long Banded Silverline (Spindasis lohita senama)



Butterfly Biodata:
Genus: Spindasis Distant, 1884
Species: lohita H. Druce, 1873

Sub-species: senama Seitz, 1926
Wingspan of Adult Butterfly: 28mm
Caterpillar Local Host Plants:
Terminalia catappa (Combretaceae), Melastoma malabathricum (Melastomataceae), Trema tomentosa (Ulmaceae), Talipariti tiliaceum (Malvaceae), Flagellaria indica (Flagellariaceae), Psidium guayava (Myrtaceae, common name: guava), Thespesia populnea (Malvaceae).


A Long Banded Silverline perching on a leaf tip.


A sunbathing male Long Banded Silverline displaying its striking upperside.

Physical Description of Adult Butterfly:
Above, both sexes are brown with an orange tornal patch on the hindwing. In addition, the male is purplish blue in the dorsal area of the forewing, as well as for almost the whole hindwing except the costal border. Underneath, both sexes are similar with a pale yellow ground colour. Both wings are traversed by 5 or 6 silverlines broadly edged with dark red or black. There are white-tipped, moderately long filamentous black tails at the end of veins 1b and 2, of which the pair at vein 1b longer is.The abdomen is striped in red to dark red.

A female Long Banded Silverline sunbathing between its ovipositing runs..


A Long Banded Silverline perching on a leaf.

Field Observations of Butterfly Behaviour:
This attractive species is uncommon in Singapore, despite the fact that it has a wide distribution across the main Singapore island. The fast flying adults have been sighted in multiple locations including Pulau Ubin, Sungei Buloh Wetland Reserve, Kranji Nature Trial, as well as iwastelands in the western and northern eastern part of Singapore. The adults seemed to have a fondness for flowers of the Mile-a-minute weed commonly found in wastelands.

A Long Banded Silverline taking nectar from flowers of the mile-a-minute.


Two close-up views of the silver lines on the wings.

Early Stages:
The immature stages of Long Banded Silverline are polyphagous and so far 6 plants have been recorded as local host. It is noteworthy to point out that one of them, Flagellaria indica, is a monocot and this is a very unusual host for a lycaenid butterfly. Caterpillars of all instars of the Long Banded Silverline feed on young to middle-aged leaves of the hosts, and have a strong association with ant species living on the same host plant.


Host plant: Sea Almond. Leaves and fruits are featured here.


Host plant: Flagellaria indica.

In the field, a typical encounter of a Long Banded Silverline caterpillar would see it being attended by many ants. It is also likely that several caterpillars, sometimes of different instars, share the same leaf. Where available, the caterpillar also takes advantage of the ant pavilion, typically constructed by the attending ants on the leaf underside, and uses it as shelter from predator or parasitoids. Such strong association with ant species has earlier been observed and documented in earlier literature on this species. This strong ant association could be a reason why caterpillars of this species never made it to adulthood when they were taken from the field and bred in captivity. Breeding from the egg stage is however possible, and so far several ButterflyCirlce members have been able to do so successfully. The following account of the complete life history of Long Banded Silverline is based on specimens bred on Sea Almond.



A video clip showing the ant-caterpillar assocation between one Long Banded Silverline caterpillar and one ant species. Note the eversion of the tentacular organs when the ant got too close.


A mating pair of Long Banded Silverline on a grass blade.


A female laying the second of a pair of eggs on the leaf upperside.
The first egg can be seen near the abdomen tip.

Eggs are laid on the leaf surface or on a petiole. When laid on the green leaf surface, the female typically seeks out a small brown patch (where the leaf has been somehow damaged previously) to lay its eggs. The eggs are laid either singly or in pairs. Each egg is initially whtiish green, but turning light brown within minutes of being laid, and eventually chocolate-brown within hours. The coloration makes the eggs almost indiscernible against the brown substrate they were adhered to. Each egg is about 0.8mm in diameter, with a thick discoid shape. The egg is coarsely recticulated with rather large and deep pits and ridges. The micropylar sits atop at the center of the upper surface.


Two views of a pair of eggs laid on a damaged and brown patch on the upperside of a leaf.

Each egg takes about 6-7 days to hatch. The young caterpillar emerges after nibbling away sufficiently large upper portion of the egg shell. Measured at a length of about 1.8mm, its pale yellow green body is somewhat flatish with four rows of moderately long fine setae running lengthwise. Each body segment has a short protrusion laterally on both sides of the body. A very long black setae and a few shorter whitish setae emanate from each protrusion. The thorax except for the dorsal area of the 3rd thoracic segment is dark red, and there is a dark and rather large prothoracic shield. The posterior segments from the 8th abdominal segment are also dark red with a large black anal plate. Two small lateral processes are discernible on the 8th abdominal segment. The head capsule is black.


Left: a pair of mature eggs. Right: one new hatched caterpillar with another still eating its way out..


Two views of a 1st instar caterpillar, early in this stage, length: 2mm.

As the caterpillar grows, its body broadens sideway. The growth is slow and after about 3-3.5 days, it only reaches about 3-3.5mm in length when it stops for the moult to the 2nd instar.


Two views of a 1st instar caterpillar, late in this stage, length: 2.8mm.

Covered with numerous short setae (each with an enlarged tip), the body of the 2nd instar caterpillar is pale yellow in base color and is flattened dorso-ventrally. The prothoracic shield is dark and much larger than in the 1st instar. There are two dorso-lateral series of small red markings on the first 6 abdominal segments. Each of the three thoracic segments and the first 7 abdominal segments bears a pair of lateral cone-shaped projections furnished with a tuft of short to moderately long whitish setae. Each of these setae is not smooth but carry a number of spikes along its length. The dorsal nectary organ is now discernible on the 7th abdominal segment. On the 8th abdominal segment, there are two prominent cone-shaped projections housing the tentacular organs. The last 2 posterior segments are fused into an enlarged flat structure carrying the black anal plate on its dorsum.


Two views of a 2nd instar caterpillar, early in this srage, length: 3.3mm.

The growth in this stage brings the caterpillar to a length of about 4.5-5mm, and after about 3-3.5 days in this stage, it moults again.


Two views of a 3rd instar caterpillar, late in this stage, length: 4mm.

The 3rd instar resembles the 2nd instar caterpillar in most aspects. Now the eversion of the tentacular organs can be readily observed. A large dorsal band, bordered by the two dorso-lateral series of dashed markings, is vaguely defined. Each of these dorso-lateral markings consists of a dark red patch flanked upwardly by a whitish patch. This instar takes 3-4 days to complete with the body length reaching about 7-8mm before the next moult.


Two views of a 3rd instar caterpillar, newly moulted, length: 4mm.

Two views of a 3rd instar caterpillar, late in this stage, length: 6mm.

The 4th instar caterpillar has a distinct dorsal band highlighted by a much darker shade of yellowish green along its doro-lateral border, in contrast to the much lighter shade in the body ground colour. A thin pale dorsal line sits in the middle of the dorsal band. The another visual difference is in the greater orange tone in the first 2 thoracic segments. This instar lasts about 3.5-4 days with length reaching 10mm.


Two views of 4th instar caterpillar, early in this stage, length: 6.5mm.
Two views of 4th instar caterpillar, late in this stage, length: 9mm.

Several caterpillars of the Long Banded Silverline taking shelter in an ant pavilion on the underside of a Sea Hibiscus leaf.

The 5th instar caterpillar has a much more prominent dorsal band due to the assumption of a much darker tone of yellow and orange in its coloration. The greater orange tone is also found in the thoracic and posterior segments. The body base colour is yellowish green in one form, and brownish in another. This instar lasts about 3.5-4.0 days with length reaching 14mm.


A 5th instar caterpillar, newly moulted, length; 8.5mm.


A 5th instar caterpillar, early in this stage, length: 9mm.


Two views of a 5th instar caterpillar, late in this stage, length: 12mm.

Compared to the earlier instars, the 6th (and final) instar caterpillar has a much darker coloration especially in the dorso-lateral series of markings. The thin dorsal line is also highlighed by flanking black lines. This instar lasts about 6-7 days with the length reaching up to 24mm.


The two late instar caterpillars in a shallow leaf shelter. The left one is about to moult to the 6th instar, and the right one is in early 6th instar.


Two views of a 6th instar caterpillar, early stage, length: 12.5mm.


Two vliews of 6th instar caterpillar, later in stage, length: 18mm.

Two final instar caterpillars found on the underside of a Sea Almond Leaf in the field.
One was partially hidden in an ant pavilion while another was feeding nearby.


Towards the end of the 6th instar, the caterpillar ceases eating and its body shortens in length as it seeks out a pupation site. In the field, one common pupation site is an available ant pavilion. Otherwise the caterpillar creates a shallow pupation shelter on a spot of the leaf surface with a number of silk threads. Within the pupation shelter, the pre-pupatory caterpillar readies itself for pupation by spinning a silk pad to the substrate. No silk girdle is used as the pre-pupa secures itself to the silk pad via the claspers at its posterior end.


Two views of a pre-pupatory larva of the Long Banded SIlverline.
Pupation takes place after 1.5-2 days of the pre-pupal stage. The pupa has the typical lycaenid shape, yellowish green in the abdomen and green in the thorax and wing pads. The pupa has a length of about 10-12mm.


Two views of a pupa of the Long Banded Silverline.
A pupa of the Long Banded Silverline found in the field. Pupa was seated within an ant pavilion.
The bottom picture shows the pupa exposed after the top of the ant pavilion was removed.


Eight days later, the pupa becomes darkened in color signaling the imminent emergence of the adult. The next day the adult butterfly emerges from the mature pupa. (Note: Based on breeding experience of ButterflyCircle members of this species, having six instars for the larval stage seems to be norm but there were exceptions where the number of instars reached up to 8.)


Two views of a mature pupa of the Long Banded Silverline.
A newly eclosed Long Banded Silverline "drying" its wings.

References:
  • The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society.
  • Life Histories of Asian Butterflies, Vol. II, Igarashi S. and Fukuda H., Tokai University Press, 2000.
Text by Horace Tan, Photos by James Chia, C K Chng, Ben Jin Tan, Sunny Chir, Khew SK and Horace Tan

5 comments:

Blue Heron Moon said...

I love your beautiful and very informative blog. As usual I learned so much from this post. Thank you.

Horace said...

You are welcome. :)
We are glad that you have found our blog posts to be useful or interesting.

haneesh said...

Great work.

Quality of content and the pictures in this blog inspires the butterfly enthusiasts in other parts of the world too..

congrats and all the best

Horace said...

Thanks, Hanessh. :)

It would be great if more butterfly enthusiasts in other parts of the world would share their finds through blogs or other online means.

Tan Yue Qian Clarissa said...

Hi, I'm Prof Antonia's student and might be doing a project on this beautiful butterfly, I wonder if anyone still breeds them? Or anyone has a pinned sample? Thanks!