Butterfly Biodata:
Genus: Pieris Schrank, 1801
Species: canidia Linnaeus, 1768
Subspecies: canidia Linnaeus, 1768
Wingspan of Adult Butterfly: 45-55mm
Caterpillar Local Host Plant: Cleome rutidosperma (Capparaceae, common name: Purple Cleome, Fringed Spiderflower).
Physical Description of Adult Butterfly:
The wings are mostly white, and dusted in black (more heavily so in the basal areas of both fore- and hindwings). On the upperside, the forewing sports a black apical border and a black post-discal spot in space 3. On the hindwing, there is a black sub-costal spot and four to five black marginal spots. The female is more heavily marked in black than the male, and has a distinct double spot in space 1b of the forewing. On the underside, the wings are mostly white in the male, and strongly yellow-dusted in the female (in the hindwing and the apical area of the forewing). In both sexes, there is a yellow basal streak along the costa on the hindwing, and there are black post-discal spots in spaces 1b, 3 and 5 in the forewing. The spot in space 5 is typically much less conspicuous than the other two.
Field Observations of Butterfly Behaviour:
This species occurs in open grassy areas and flies in the company of the Striped Albatross and Psyche, both of which share the same local host plant with the Cabbage White. It is a weak flyer, and keeps close to the ground looking for flowers to feed on. On sunny days, it flies restlessly, and rarely stops for long. The species can occasionally be found in wastelands, farm ways and parklands and is sometimes common where it occurs. Often, several individuals are seen at one time, especially in the vicinity of the host plant. The males have the habit of puddling for mineral intakes. Although C&P4 described the Cabbage White as not uncommon in Singapore, sightings of this species, however, have become much less frequent in the past years.
Early Stages:
The recorded local host plant for the Cabbage White, Cleome rutidosperma, is a common herbaceous weed with violet-blue to pink flowers. Caterpillars of the Cabbage White feed on the relatively young to middle-aged leaves as well as young shoots, stems and flower parts. A noteworthy feature is that caterpillars of Cabbage White, in all instars, possess a prosternal gland, on the ventrum of the prothorax. This gland is present in a limited number of butterfly species,and it is everted when the caterpillar is roughly handled. Past studies have found it is capable of emitting chemicals with a defensive function.
Eggs of the Cabbage White are laid singly on a leaf of the host plant. The pale yellowish egg is cylindrically-shaped with a narrowing upper end, and has a height of about 1mm. It has vertical ridges and numerous transverse striations. The vertical ridges end in low projections encircling the micropylar at the upper end.
The egg takes about 3 days to hatch. The newly hatched has a length of about 1.8mm and a pale yellowish head capsule. Its cylindrically-shaped body is in a stronger shade of yellow and featuring sub-dorsal, dorso-lateral and lateral rows of small tubercles running lengthwise. Each tubercle has a moderately long setae emerging from the middle of it. The end of each setae bears a tiny droplet.
The newly hatched eats the empty egg shell for its first meal, and then moves on to eat the leaf lamina. Its body takes on a strong green undertone with the intake of leaf diet. In 2.5 days, the caterpillar grows to a length of about 3mm before the moult to the 2nd instar.
The 2nd instar caterpillar is yellowish green in body color with similar droplet-bearing setae as in the 1st instar. In addition, there are numerous small, black, conical tubercles dotting the body surface. Each of tubercles has a short black setae emerging from it. This instar lasts about 1.5 to 2 days with the body length reaching about 5.5mm.
The 3rd instar caterpillar resembles the 2nd instar caterpillar closely except for the appearance of a faint yellowish dorsal band and a spiracular series of small yellow markings. The head capsule is now yellowish green. This instar takes about 2 days to complete with body length reaching about 9mm.
Again, the 4th instar retains all the features as the 3rd instar. In addition, numerous fine and white setae, in greater proportion than in early instars, now adorn the body surface. This penultimate instar lasts about 2 days with body length reaching about 15.5mm.
The 5th and final instar caterpillar resembles the 4th instar caterpillar closely. Its yellow dorsal band is more prominent than in the 4th instar. The many black tubercles dotting the bluish green body surface gives its a distinctive speckled appearance. The 5th instar lasts for 2.5-3 days, and the body length reaches up to 25mm.
On the last day of the 5th instar, the caterpillar ceases feeding and its body gradually shortens. It wanders around and comes to rest on the underside of a stem/stalk or a leaf of the host plant or adjacent plants. Here the caterpillar spins a silk pad and a silk girdle to secure itself and then becomes immobile in a head-up pre-pupatory pose.
Pupation takes place about 0.5 day later. The greenish, black-speckled pupa secures itself with the same silk girdle as in the pre-pupal stage, but with cremaster replacing claspers in attaching the posterior end to the silk pad on the stem/leaf surface. It sports a yellowish, thoracic dorsal ridge which is sharply raised at thoracic segment 2. This ridge ends in a pointed, yellow-tipped cephalic horn at the anterior end. The abdominal segments 2-4 are produced laterally into a black pointed tooth at each side of the abdominal segment 2. The dorsum is whitish on the anterior side of this transverse edge. In addition, two lateral whitish ridge lines run lengthwise along the entire length of the body. Length of pupae: 17-19mm.
Top panel features a male pupa and the bottom panel a female pupa.
After about 6 days of development, the pupal skin turns translucent as the development within the pupal case comes to an end. The markings on the forewing upperside become discernible and indicative of the gender of the soon-to-emerge adult. The following day, the adult butterfly emerges from the pupal case.
References:
- [C&P4] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society, 1992.
- A Field Guide to the Butterflies of Singapore, Khew S.K., Ink On Paper Communications, 2nd Edition, 2015.
