Varied Eggfly

Naming

Listed alphabetically:
⤷ "H. b. bolina" –
⤷ "H. b. constans" –
⤷ "H. b. enganica" Fruhstorfer, 1904 –
⤷ "H. b. gigas" –
⤷ "H. b. incommoda" Butler, 1879
⤷ "H. b. inconstans" Butler, 1873 –
⤷ "H. b. jacintha"
⤷ "H. b. jaluita" Fruhstorfer, 1903
⤷ "H. b. kezia" –
⤷ "H. b. kraimoku" –
⤷ "H. b. labuana" Butler, 1879 –
⤷ "H. b. lisianassa" –
⤷ "H. b. listeri" Butler, 1888 –
⤷ "H. b. montrouzieri" –
⤷ "H. b. naresii" Butler, 1883 –
⤷ "H. b. nerina" –
⤷ "H. b. pallescens" –
⤷ "H. b. philippensis" –
⤷ "H. b. pulchra" –
⤷ "H. b. rarik" Eschscholtz, 1821) –

Distribution

"H. bolina" is found in Madagascar in the west, through to South and Southeast Asia, Cambodia, the South Pacific islands, and occurs in parts of Australia as far south as Victoria during summer and autumn, Japan, and New Zealand. Appearances in New Zealand appear to be linked with favourable winds during April–June migratory periods in Australia, with the butterfly being recorded in 1956, 1971 and 1995. No populations have established locally in New Zealand.

Behavior

Males are notably territorial. Individuals are known to return to defend the same location for up to 54 days, with site fidelity increasing with age. Territories that enhance the visual detection of adult females are preferred.

Unlike congenerics such as "Hypolimnas anomala", female "H. bolina" most often lay one or two eggs at a time. These are typically laid on the leaf underside. Early season females in the Australian wet-dry tropics target freshly-germinated seedlings of their favoured host in this region, "Synedrella nodiflora". Eggs hatch after 3 days under a constant incubation temperature of ca. 25 degrees C. Newly hatched larva first consume their egg shell before feeding on the leaf upon which they were laid. Later larval instars are highly mobile and readily disperse in search of new host foliage. Individuals rarely pupate on their host plant.

Habitat

"H. bolina" is a generally common butterfly across most tropical and sub-tropical habitat types, including wet/dry woodland, rainforest and shrubland. It is a common visitor to suburban back yards and other areas of human disturbance. In the Australian tropics, "H. bolina" is particularly common along tracks, streambeds, and the corridors formed between remnant gallery forest and cultivated sugar cane fields. Both sexes are invariably found in association with one or more larval hostplant species, especially disturbance species such as "Synedrella nodiflora", "Sida rhombifolia", and "Commelina cyanea".Males are notably territorial. Individuals are known to return to defend the same location for up to 54 days, with site fidelity increasing with age. Territories that enhance the visual detection of adult females are preferred.

Unlike congenerics such as "Hypolimnas anomala", female "H. bolina" most often lay one or two eggs at a time. These are typically laid on the leaf underside. Early season females in the Australian wet-dry tropics target freshly-germinated seedlings of their favoured host in this region, "Synedrella nodiflora". Eggs hatch after 3 days under a constant incubation temperature of ca. 25 degrees C. Newly hatched larva first consume their egg shell before feeding on the leaf upon which they were laid. Later larval instars are highly mobile and readily disperse in search of new host foliage. Individuals rarely pupate on their host plant.

Reproduction

The eggs are a pale, glassy green with longitudinal ridges except on the top.

Evolution

On the Samoan Islands of Upolu and Savai'i, a parasite had been killing the male members of "Hypolimnas bolina". The problem was so severe that by 2001, males made up only 1% of the population. However, in 2007, it was reported that within a span of just 10 generations, the males had evolved to develop immunity to the parasite, and the male population increased to nearly 40%. This evolutionary event involved changes at a single genomic region on chromosome 25, and represents one of the fastest examples of natural selection observed to date in natural populations. Ed Yong has written a popular science account of this highly unusual evolutionary event.