Bhutanitis thaidina comes last, alphabetically, of the four species of Bhutnnitis. (Some sources count more than four species but most scientists classify the additional types as subspecies of thaidina.) Historically it came first. Though not common or easy to find, it was less rare and hard to find than the others. Its name recalls a character from ancient literature, Thais, a legendary beauty. Did Thais ever have a daughter? Anyway, another butterfly was named thais so this one was thaidina, a Roman-style name for Thais' Daughter.
Here is a long rambling paper, written for an audience who liked detailed travel stories, about the butterflies, their habitat, and how they got their name. (In French.) The reprint that made it into the book photocopied here is believed to be the first non-Chinese article written about these butterflies.
Photo from Earth Unreal, documenting that, though rare, thaidina can be locally abundant at the right place and time. And, when they are, they congregate at puddles. Though not really endangered, their populations are scattered and localized enough to be always at some risk.
A few other species in this genus have been named and determined to be subspecies of thaidina. Full information about each subspecies was not available, at least not in English. These butterflies live at a minimum altitude of a mile above sea level, so they've not been as exhaustively studied as other showy, popular Swallowtails.
It's been celebrated on a postage stamp:
Photo from touchstamps.com.
Studying butterfly behavior is fun. Some lucky scientists got funding for a three-year study of how and why wildlife population estimates tend to be wrong.
There is also the fascinating (at least, when taking an interest in it means spending months or years in the mountains rather than at school in a polluted city) question of why thaidina forms a vestigial sphragis after mating. The female butterfly has a passage through which the spermatophore gets inside and one through which the eggs get outside. The sphragis forms when butterfly body secretions dry on the outer surface after mating, apparently holding the spermatophore in and preventing other spermatophores from being admitted. It incorporates loose scales and hairs from the male butterfly, presumably adding a whiff of his scent to the female's scent. However, with time and determination, a couple of butterflies can use fresh, wet body secretions to dissolve an old sphragis, transfer a second spermatophore from male to female, and form a new sphragis. The sphragis is sometimes described as a "chastity belt," but, like those devices, it prevents only hasty or unplanned "unchastity."
Both male and female butterflies release most of their viable reproductive cells the first time they mate. Their lives are short and uncertain; many, probably most, have only one opportunity to mate, so there would be little survival advantage in saving viable reproductive cells for later, as longer-lived animal bodies do. Both male and female butterflies instinctively seek mates who have not mated before. In some species it's possible even for humans to tell which individual butterflies have mated; a sphragis is one of the indicators we can see, though butterflies seem likely to rely on scent. The sphragis does not need to make second or third matings impossible if its function is to make it obvious that a female has mated before. Most males will keep looking for a female without a sphragis, thus ensuring maximal DNA dispersal.
So thaidina, and also Bhutanitis lidderdalei and ludlowi, when examined closely, show a small inconspicuous dot of a sphragis that often fails to cover the sperm passage. Nature's design in their case seems to be not to discourage second matings, but to give male butterflies fair warning.
In 2021 a thaidina family was successfully reared in captivity: One female butterfly laid 36 eggs, which produced 25 caterpillars, which yielded 9 pupae, from which emerged 3 butterflies, which is a typical rate of reproductive success for butterflies. It was headline news!
In addition to their generous supply of "tails" on the hind wings, and their barely discernible sphragides, another feature these butterflies have in common with other Bhutanitis species is--literally--hairy eyeballs:
Photo by LC Goh. Surface scales all over these butterflies' bodies extend into hairs. The eyes are actually compound, with room for hairs to grow between the ocelli that make up each big black eye. Like the smaller mountain Swallowtails in Europe, these butterflies' bodies look furry at close range. The hairs probably provide some insulation against heat and cold.
As with other Bhutanitis, the upper surface is usually colorful while the underside of the wings is pale and reflective. Even on the upper surface, however, the red and yellow color can fade.
Photo by Geilsloi.
Caterpillars are vulnerable. (This is news? All caterpillars are vulnerable.) Though they eat a species of Aristolochia and are toxic to birds, they're still vulnerable to ants and spiders that tolerate their toxicity. They seem to do best in open glades where they receive some shade and insulation from large trees overhead, with relatively few lower shrubs.
Obviously Chinese lepidopterists know what the early stages of these butterflies look like, but neither photos nor descriptions in English for the early life stages are available online. European naturalists did not describe any conspicuous differences between early stages of thaidina and the other species, so they probably look similar, as do the adult butterflies.
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