The Chestnut Tiger 青斑蝶 (qīng bān dié) Parantica sita niphonica is a common large butterfly found throughout Asia. It has a 43-65 mm wingspan and a striking window pane pattern of dark and light splotches on the wings.
Chestnut Tiger 青斑蝶 (qīng bān dié) Parantica sita niphonica
Chestnut Tigers are in the Danaidae family 斑蝶亞科 (bān dié yà kē) or milkweed butterflies, distinctive for their pair of vestigial front legs, useless for walking. Milkweed butterflies lay their eggs on various milkweeds on which their larvae (caterpillars) feed. Other common milkweed butterflies include the Striped Blue Crow 異紋紫斑蝶 (yì wén zǐ bān dié) Euploea mulciber barsine, Common tiger 虎斑蝶 (hǔ bān dié) Danaus genutia and the Monarch 帝王蝶 (dì wáng dié) Danaus plexippus (in North America). Despite their large size, chestnut tigers are rarely hunted by birds, probably because their bright colors indicate they have tough bodies and taste bad (aposematic).
Food
Foods of the chestnut tiger include tropical milkweed 馬利筋 (mǎ lì jīn) Asclepias curassavica, and brown hemp 菽麻, 太陽麻 Crotalaria juncea. The larvae use plants from the family Apocynaceae (milkweeds), which often contains latex-like compounds in the stem as hosts. Nectar from flowers in the milkweed family are a favorite food. Males makes a pheromone for attracting females from the nectar of Crotalaria 豬屎豆屬 (zhū shǐ dòu shǔ). Male chestnut tigers are know to use pyrrolizidine alkaloids for the production of danaidone in the alar scent organ. Males of the chestnut tiger butterfly, Parantica sita, secrete danaidone as a major component from the alar androconial sex organ. Danaidone has been postulated to be derived from various pyrrolizidine alkaloids, which males ingest as adults from pyrrolizidine-alkaloid containing plants.
Chemistry
Pyrrolizidine alkaloids (PAs), sometimes referred to as necine bases, are a group of naturally occurring alkaloids based on the structure of pyrrolizidine. Pyrrolizidine alkaloids are produced by plants as a defense mechanism against insect herbivores. More than 660 PAs and PA N-oxides have been identified in over 6,000 plants, and about half of them exhibit hepatotoxicity (damaging to the liver). They are found frequently in plants in the Boraginaceae, Asteraceae, Orchidaceae and Fabaceae families; less frequently in the Convolvulaceae and Poaceae, and in at least one species in the Lamiaceae. It has been estimated that 3% of the world’s flowering plants contain pyrrolizidine alkaloids. Honey can contain pyrrolizidine alkaloids, as can grains, milk, offal and eggs. There is no international regulation of PAs in food, unlike those for herbs and medicines. Unsaturated pyrrolizidine alkaloids are hepatotoxic, that is, damaging to the liver. PAs also cause hepatic veno-occlusive disease and liver cancer. PAs are tumorigenic. Disease associated with consumption of PAs is known as pyrrolizidine alkaloidosis.
Migration
Chestnut tigers appear once or twice a year, depending on the weather and food conditions. They can found in cities and countryside, from sea level to high mountains. Despite their apparent laziness, chestnut tigers can fly at great altitudes and cover great distances. By drifting along on seasonal winds. The butterflies store fat in their abdomen to get them through the long journey. From April to June, they migrate northwards; from September to November, they return south to lay eggs. Many chestnut tigers travel over one thousand kilometers. The best information on Asian butterfly migrants is from Taiwan, where tens of thousands of purple crows travel to the south of the island for the winter and north again in the spring. Chestnut tigers marked in Taiwan have been found in Japan in the summer and others marked in Japan have made the reverse journey in the autumn. It is believed that relatively few chestnut tiger individuals undertake such marathon flights, doing so only when unusual monsoon winds are favourable. There are annual gatherings of danaids in Hong Kong, which indicate substantial seasonal movements.
Natural Taiwan 