09 November 2012

Life History of the Leopard Lacewing

Life History of the Leopard Lacewing (Cethosia cyane)

Butterfly Biodata:
Genus: Cethosia Fabricius, 1807
Species: cyane Drury, 1773
Wingspan of Adult Butterfly: 80mm
Caterpillar Local Host Plants: Passiflora foetida (Passifloraceae), Adenia macrophylla var. singaporeana (Passifloraceae)

A female Leopard Lacewing visiting the flower of Bidens alba.

A female Leopard Lacewing.

A female Leopard Lacewing showing its uppersidevisiting Lantana flowers.

Physical Description of Adult Butterfly:
Above, the male is orange with apical two-thirds of the forewing black with a white and oblique band lying within. The termen of both forewing and hindwing  is indented and lined with a broad and black marginal area containing a lace-like pattern of white markings. The female is mostly similar but with the orange background replaced with a  pale yellowish to whitish coloration, and has its hindwing endowed with more discal and postdiscal black spots.    Underneath, the wings are variegated with orange, red, white, black and blue. In the forewing, the cell area is transversed with bars of black, bluish-white and  red coloration, beyond which a broad, white and oblique band lies just below the subapical area. In the hindwing, the ground colour is orange in the male and pale creamy yellow in the female. The basal area and the costal margin are crossed by short black lines, with the ground colour more reddish in the male. A somewhat broad discal band and a narrow post-discal band, both white, are  bordered with  black spots and striae.  As in the upperside, the terminal margins are black and house lace-like white markings, with additional short white straie pointing from the margin inwards to the tip of the V-shaped markings. 

A male Leopard Lacewing showing its upperside.

A male Leopard Lacewing visiting flowers.

Field Observations of Butterfly Behaviour:
This migrant species was recently discovered in Singapore in 2005. Since then, it has established a firm foothold and can be considered a common species in Singapore. Across the island, Leopard Lacewing can be found flying in many wastelands where its host plant, Passiflora foetida, grows in relative abundance. The adults have the habit of visiting flowers for nectar and are very fast on the wings.

Early Stages:
The local host plant adopted by Leopard Lacewing as it spread quickly across the island is Passiflora foetida, a member of the Passifloraceae family commonly found in wastelands. In captive setting, the Leopard Lacewing has also been breed succesfully on another plant in the same family, Adenia macrophylla var. singaporeana, a plant which only occurs naturally within the catchment reserves. This might account for the sightings of Leopard Lacewing in some areas of the nature reserves.

Host plant : Passiflora foetida

The caterpillars of the Leopard Lacwing feed on the leaves, young shoots and outer surface of older stems of the host plant. The Leopard Lacewing caterpillars are gregarious throughout all five instars, often eating (leaves and stems), resting and moulting together in groups.

A mating pair of Leopard Lacewing.

A female Leopard Lacewing caught in the act of ovipositing.

A mother Leopard Lacewing lays eggs on its host plant in a large and loose cluster on the surface (usually the underside) of a leaf, or on a young stem and even on a tendril. Each yellowish egg is barrel-shaped with a ribbed surface. It has a height of about 1.3-1.4mm, and a cross-sectional diameter of about 0.8-0.9mm.

A small group of eggs laid on a young stem.

A loose cluster of eggs laid on the underside of a leaf.

Top: A group of fresh eggs laid on a tendril of Passiflora foetida. Bottom: Young caterpillars emerging from the eggs 5 days later.

Each egg takes about 5-6 days to hatch. The infant caterpillar nibbles away a small portion of the egg shell and pushes its way through the crack. Unlike the newly hatched of many other Nymphalidae species, it does not turn around to devour the empty egg shell. The newly hatched has a cylindrical body in yellowish brown, and an initial body length of about 2.2mm. The body is covered in a grid of greyish tubercles, each with a single long seta. The head is black and there is a pair of greyish spines on the first thoracic segment. A greyish to black anal plate is present. The young caterpillar either skims the lamina on a young leaf or nibbles away at the tip of a young stem.

Mature eggs with the black head and black body setae of the caterpillar visible through the egg shell.

Two views of a newly hatched caterpillar, length: 2.2mm.

A group of 1st instar caterpillars resting between feeds, day 2 in this stage, with color changes.

As the 1st instar caterpillar feeds and grows, its body segments take on alternating yellow and white coloration. It grows to a length of 5.5-6mm in the 1st instar, and the moult to the 2nd instar takes place after about 2-3 days in this isntar.

1st instar caterpillar, day 3 in this stage, ready to moult; length: 5mm.

The 2nd instar caterpillar is wine-red in most segments, creamy yellow in 2nd, 4th, 6th and 8th abdominal segments, mostly yellow but with a touch of wine-red in all 3 thoracic segments. The rows of tubercles in the 1st instar are replaced by 6 longitudinal rows of fine-pointed black spines, 3 to each side of the body. Among these, the dorso-lateral rows of spines are the longest. A pair of short and black coronal spine appears on the head. This instar lasts 2-2.5 days with the body length reaching about 9mm before the next moult.

A group of two 2nd instar caterpillars, length: 6mm.

Two views of a 2nd instar caterpillar, late in this stage, 9mm.

In the 3rd instar, there is no drastic change in physical appearance except for proportionately longer coronal spines (now about the same length as the height of the head capsule). A pink reddish dorsal patch can be seen in the 2nd thoracic segment, 1st, 3rd, 5th, 7th and 9th abdominal segments. This instar takes 2-3 days to complete with body length reaching up to 14mm.

Two views of a 3rd instar caterpillar, 14mm.

A group of 3rd instar caterpillars on a vine of the host plant in the field.

The coronal spines in the 4th instar caterpillar are again longer proportionately with the length of each spine about equal to the 1.5x height of the head capsule. The pinky red dorsal patch on the 2nd thoracic segment seen in the earlier instar is no longer present, with only an outline still visible. The 4th instar lasts about 3-4 days with body length reaching about 22mm.

A Leopard Lacewing caterpillar moults from 3rd to 4th instar.

Two views of a 4th instar caterpillar, late in this stage, length: 21.5mm.

A group of 4th instar caterpillars munching on a vine of the host plant.

The next moult brings the caterpillar to its 5th and final instar. The caterpillar is little changed in appearance coming into this instar. One visible change is that the coronal spines are now about 2x the height of the head capsule. This phase lasts for 4-5 days and the body length reaching up to 39mm.

Two views of a 5th instar caterpillar, early in the stage, length: 23.5mm

Two views of a 5th instar caterpillar, length: 32mm

Towards end of 5th instar, the caterpillar ceases feeding and wanders around in search of a suitable pupation site. Finally the caterpillar finds a spot on the underside of a leaf, stalk or stem where it spins a silk pad to which it secures itself with claspers at its posterior end. From this anchor, the caterpillar hangs vertically head-down and becomes a pre-pupa.

A pre-pupa of the Leopard Lacewing.

Pupation takes place a day later. The pupa hangs vertically. It has two pairs of pointed white processes at the middle of its body and a number of less prominent dorso-lateral processes. A pair of black foliaceous processes adorn the head. Body color is either dark brown or yellowish brown, both mottled with white and black patches. There are several dorsal spots of bright silverish. When disturbed, the body could jerk sideways through the movement of the posterior abdominal segments. Length of pupae: 26-28mm.

A Leopard Lacewing caterpillar moults to its pupal stage.

Three views of a pupa of Leopard Lacewing; dark form.

Three views of a pupa of Leopard Lacewing; yellowish brown form.

After about 6 days of development, the mature pupa are darkened, especially in the wing spad. The next day the adult butterfly emerges from the pupal case.

Three views of a mature pupa of Leopard Lacewing; yellowish brown form.

A female Leopard Lacewing emerges from its pupal case.

Newly eclosed Leopard Lacewing drying its wings on the pupal case. Left: female; Right: male.

  • [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, 1st Edition, 2006.
  • A Field Guide to the Butterflies of SIngapore, Khew S K, Ink on Paper Comm. Pte. Ltd, 2010.
Text by Horace Tan, Photos by Anthony Wong, Antonio Giudici, Bobby Mun, CK Chng, Caijin Huang, Jonathan Soong, Mark Wong, Sunny Chir and Horace Tan

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