Catopsilia pyranthe crokera (W.S. Macleay) (White Migrant)
This image is of the male dark form
Interesting aspects: The butterfly occurs as pale and dark forms that differ mainly in the width of the black colour along the wing margins, which is better developed in the dark forms, and that the dark form has black antennae while the pale form has pink antennae. Both forms fly together and can be produced from the same batch of eggs. Genetic dominance studies have not been undertaken. It has been reported that in southern Queensland only the dark form is present from January to March, and only the pale form between May and September. Both forms flew during April, while very few butterflies occurred between October and December. Both forms reach South Australia during migrations, with the dark form being the most common, although the pale form extends the furtherest south.
Observations in the eastern states indicate that the early stages of the butterfly are unable to survive frosts or extended cold periods. The butterfly is the most cold tolerant of the Catopsilia species.
Larval food-host: Cassia and Senna spp, the tropical and subtropical varieties with larger flowers, including **C. brewsteri (cigar cassia), *C. fistula (golden shower), **S. barclayana (pepper-leaf senna), **S. occidentalis, S. planitiicola (yellow pea or arsenic bush) (Caesalpiniaceae).
Flight period in S.A.: The butterfly is seen all year round in the tropical north of Australia. It migrates south during the southern warmer months, particularly during the monsoon wet period. Breeding numbers fluctuate from year to year, affecting the migration. Those reaching southern areas of South Australia and Victoria usually arrive in April. Migrating butterflies are usually recorded from February through to May in South Australia, but odd butterflies have recently been recorded during mid-September from the Innamincka Regional Reserve in the far north-east of the state, and again during early October near Marla in the Far North Region.
Distribution: Normally a tropical and subtropical butterfly. It is a very strong migrant and at irregular intervals immense numbers fly south from the tropics, usually reaching as far south as Sydney in New South Wales in the east of Australia, but rarely to the southern settled areas of South Australia and Victoria. Major flights in South Australia occurred in 1940 and 1955. Other records for the state are 1887, 1898, 1934, 1970, 1973, 1974, 1984, 1988, 1997 and 2000.
Habitat: The butterfly normally requires tropical, humid woodland habitat. The hostplant Senna planitiicola occurs sporadically in the extreme far-north of the state, while the introduced hostplants Cassia fistula, Senna barclayana and S. occidentalis are sometimes grown in the homesteads and town gardens of the far-north. It is possible that opportunistic breeding may occur in those areas during favourable years. The butterfly is not biologically suited to the temperate conditions of southern South Australia, although it successfully bred once on Senna planitiicola at the Waite Arboretum in Adelaide during the autumn of 1955.
Conservation Status in S.A.: A migrant. Common in the north of Australia.
Threats: No major threats.
Conservation Strategy: None required.
Author: R. GRUND, © copyright 15 December 1999, all rights
Last update 20 January 2002.