Wednesday, January 18, 2023

Butterfly of the Week: Atrophaneura, or Pachliopta, or Papilio Aristolochiae

Today's butterfly is a Swallowtail, so first it was classified as a member of the genus Papilio. Then when Papilio was divided into smaller genera, the red-bodied, dark-winged swallowtails of southern Asia were renamed Atrophaneura. Recently Atrophaneura has been split into further genera, and the butterfly whose English name is "Common Rose" was renamed Pachliopta aristolochiae. The species name aristolochiae, "of the Aristolochia vine," has always been the same. 

The butterfly is quite common across the southern half of Asia, India, China, from Afghanistan south to Sri Lanka and Java. Flitting through meadows and woods, it's not easy to overlook.


Phoro donated to Wikipedia By Peellden - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=36445544

The fore wings can look black with white, dark grey with light grey, or rusty brown, and the hind wings are black or dark brown with varying patterns of white and red or pink spots. Females have somewhat broader wings and may show more red spots on the top side of the hind wings than males. Males have brighter red spots on the underside of the hind wings. Markings can identify sub-species (there are currently said to be about twenty sub-species) and whether individuals matured in dry or rainy weather. The "rose" coloring may fade to orange, brown, or white; not all individuals show red or bright rose-pink colors.


Photo donated to Wikipedia By Sandew LA - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=107317200 ,

The Common Rose is common enough to be found in large groups in some places, and is not regarded as endangered. It survives urbanization. However, some local populations even of this abundant species are threatened by human activity. The species is popular and familiar, and has been featured on a postage stamp in Malaysia.

These butterflies fly earlier in the day than other species do, and later in the evening. They may take a siesta on a hot afternoon. They sometimes gather at puddles. This one doesn't seem to mind being the only Common Rose in a crowd of smaller butterflies:


Photo by nliew66butterflies.blogspot.com. 

Oddly, although I found photos of these butterflies perched on human hands, showing that they're only medium-sized for Asian swallowtails--about the size of our black swallowtails, smaller than our tiger swallowtails--I didn't find typical measurements. 

Pachliopta, the "large-tailed" swallowtails, differ from Losaria, the "club-tailed" swallowtails, in having larger tails overall and more conspicuously using the tails to help steer themselves through the air. Other swallowtail butterflies seem to use the tails primarily to confuse predators. It's a "both and" rather than an "either or" question. Large-tailed swallowtails sometimes do lose a tail to a predator, and other swallowtails probably get some steering benefits from their tails. 

The Common Rose flies higher than most butterflies, often flying and roosting five yards above the ground. Its flight looks "peculiar" because it uses its fore wings for propulsion and its hind wings for steering. It flies slowly and dives down onto flowers. The effect can be to look as if the butterfly had lost the use of its hind wings first and then lost the use of its fore wings as well...but nothing is wrong with the animal; it is moving in the normal way for its kind. 

It is not as concerned about camouflage or hiding as most butterflies are, because its black-and-red colors warn most predators that it's not good to eat. As with other big colorful butterflies, the colors look pretty to lifeforms, such as humans, who don't normally eat insects anyway, but their important function is to advertise that the butterfly has absorbed toxins from leaves it was adapted to eat, as a caterpillar, and is therefore poisonous when swallowed. Even as an adult it exudes an odor and sometimes fluids that even humans often describe as unpleasant. Its secretions have been chemically analyzed: 


Though some individuals show black and red colors more clearly and others are more brownish, the colors are consistent throughout this butterfly's life cycle. Eggs are little round red beads with fine black markings. Mother butterflies carefully select healthy, growing leaves and shoots on which to place just one egg at a time. Eggs may be placed on either side of a leaf or at the base of a new leaf: There are known to be six species of Aristolochia and one other vine on which the caterpillars can survive. 


Photo donated to Wikipedia by Sandew LA. The mother butterfly placed this egg where it would be likely to hatch just about the time the new leaf unfolded.

Caterpillars are dark reddish black with reddish tubercles and a whitish "belt" near the middle. They are skin eaters. Nature's way of controlling several large butterfly and moth species populations is that the caterpillars have no social instincts. If two caterpillars do meet, their instincts will tell each one to try to eat the other skin. They may initially be surprised to find a skin of their own species that doesn't belong to them, but all caterpillars live to eat.


Photo donated to Wikipedia By J.M.Garg - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=5326679

The pupa is the least colorful phase of this butterfly's life, and may be the most vulnerable. Its shape seems unusually convincingly camouflaged to suggest a dead leaf.

Photo donated to Wikipedia By © 2016 Jee & Rani Nature Photography (License: CC BY-SA 4.0), CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=51024568

Adult butterflies usually fly for only about two weeks.


Photo by Lubomir Klatil at biolab.cz. 

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