Though it's in a separate genus, lives on a different continent, and can't crossbreed with Cressida cressida, scientists think the rare, possibly endangered Euryales corethrus is more similar to Cressida cressida than other species are. For one thing, corethrus has "Clearwing" as one of its many common names, and in Mexico (where it is exotic) it's called Aceitosa de litoral, the Littoral or Coastal Greasy. It, too, tends to lose its colorful wing scales easily and show thick, transparent wings that remind people of oily paper.
Photo from Faunaparaguay.com.
It's certainly colorful while its colors last.
Photo from ecoregistros.org.
It's featured in this very pretty printable album of the world's Swallowtails:
Native to Brazil, Uruguay, Argentina, and Peru, this butterfly is threatened by habitat loss, "climate change," and "pesticides." No points for guessing which of the threats to it is being studied by people who want funding. No points for guessing which, if explored, would be most likely to restore butterfly populations. (A good bit of what's been written about this species is in Portuguese or Spanish but, because of its increasing rarity, informative articles are also available in French and Japanese. Currently available online are reprints of the Annales de la Societe Entomologique de France for 1878, when the Societe considered this species at some length.) The link below is worth reading in Portuguese as best you can; Professor Atencio has more to say in the original than in the Google Translated version.
In support of the position that pesticide poisoning and habitat loss are more relevant to this butterfly's survival than "climate change," this 2012 study found the butterflies moving into a nature preserve.
But see what kind of computerizd cobweb-spinning gets published. The corporations growing rich from the sale of toxic "pesticides" love it when people spend their energy on theoretical projections that are disproved and replaced every few years.
Carvalho Costa more accurately pinpoints "shrinkage of native grassland where the host plant can be found." The host plant for eurythrus is Aristolochia sessilifolia.
The variable that's easiest to test is, of course, the "pesticides." Suspend use for five years; see if populations rebound. But, but...that'd be five years without profits, the companies whine. Boohoohoo WAAAHHH! They can't do without profits--even temporarily! They can't give money to politicians if they don't keep growing their profits! In the smaller, healthier governments our world needs, an essential qualification for government employment will be a proven record of willingness to crack down on these companies. The bigger and more profitable a corporation is, the higher and more rigorous the standards to which it needs to be held.
Why is it called Euryales corethrus? Part of the tradition of naming Swallowtails after characters in ancient literature. Some specified "heroes." Euryales, in the Odyssey, was hardly a heroic figure. While Odysseus was off on his adventures, heroically telling kings that he couldn't marry their beautiful daughters and inherit their kingdoms because he loved Penelope, you may remember the suitors who were making Penelope's life difficult. Penelope loved Odysseus, too, but the suitors insisted that he must be dead and that her subjects would never accept a ruling queen. Some of them are noted as having accomplished something, at least been somebody's son, or formed an alliance with one of the women helping Penelope run the farm. Euryales is named as being the one the half-grown son personally killed when Odysseus came home and sentenced the suitors to death. Possibly the naturalists who stuck his name on to a defenseless butterfly were confusing him with a more heroic character.
Or were they prescient? In the Odyssey, Euryales' epitaph could have been "The one the fourteen-year-old boy killed." What mental age are people "being" when they cling to the idea that "pesticide" poisoning will solve problems with "pest" species? Will Eurytides corethrus be "The one the mental-equivalents-of-a-four-year-old boy killed"?
Corethrus could easily be a Latin adjective but Google's Latin dictionaries don't list it as one. Korethros is Greek for a broom or sweeping brush. That would make sense as a name for a "Brush-footed" butterfly, but Swallowtails are a different family; their six legs are all fairly long, and no pair of legs is held up like "brushes" or hands. Boisduval, who officially described the species in 1836, credited his friend Lacordaire with both the name and the specimens they described but did not mention any particularly brushy-looking features. (They weren't even exactly sure where their specimens had come from but thought they were from "some place in America"...)
In other languages it has several other names. Grassland Swallowtail, Clearwing, Clear-Winged Swallowtail, Aceitosa de litoral, but no name has really stuck. This butterfly seems too uncommon to have a common name.
Photo by Biologodepracinha/
There may be four generations a year; the butterfly is found in "February, April, May, September, October, and December" in Brazil, according to Marcelo Carvalho Costa. The butterflies don't travel fast; when researchers caught, marked, and released them, about one in six males and one in ten females was caught in the same place on another day. Populations are very local, not hard to find in the right place at the right time. In the past they were described as abundant; now, overall, they're described as very rare.
Males tend to be more colorful than females. Size tends to be determined by temperature more than sex; individuals vary, but the biggest ones fly in December. The wings can be quite large, with a wingspan of 4 inches or more possible in December. Males and females also differ in behavior; females spend more time looking for host plants, while males spend more time chasing other butterflies, male or female. Females place one egg on a leaf but may lay four or five eggs on one large vine.
Females can look pale brown or orange. Markings vary, especially on females who, like so many female butterflies in the Swallowtail family, can look similar to or different from males. This species lacks "swallow tails," but because of the structure of its wings it's part of the Swallowtail family anyway.
Photo by Inesavasconcelhos.
This pair, photographed by Lucaskaminski, stayed together long enough for him to snap half a dozen clear pictures. Nature photo sites are supposed to limit photos of the same animal but, in this case, Lucaskaminski may have documented extended mating behavior in this species, similar to the 14-to-48-hour marathon matings of Cressida cressida.
Like Cressida cressida, Euryales corethrus form sphragides, large (relative to their overall size) plates of congealed body secretions that adhere to the back end of the female after mating and make a second mating more difficult. Albert George Orr, who interpreted Cressida mating behavior as like rape despite its being actively sought by females, saw mated female butterflies as displaying their sphragides to persuade males to leave them alone. Ana Paula dos Santos de Carvalho, noting that male butterflies' DNA is better preserved when females mate only once whereas females' is better preserved if females mate twice, saw the sphragis as a "chastity belt" males impose on females. However, although the sphragis of Euryales corethrus is prominent and proudly displayed, a determined pair of butterflies can dissolve and/or dislodge it, and Carvalho also noted finding females with multiple sphragides. Male butterflies prefer virgin brides when they can get them (and females prefer virgin bridegrooms) but their lives are short, and they'll take what they can get. Apparently a male would rather go to the extra effort of secreting the biochemicals that can dissolve a sphragis than risk not finding a mate at all.
The early stages of these butterflies' lives are not well documented. Eggs are probably little round beads dotted with droplets of aristolochic acid, but nobody has posted photographic evidence.
Caterpillars share the warty skin and mix of red-black-and-white pigmentation that is typical of Aristolochia-eating Swallowtails. I found one photo online.
Photo by Anapsc, which is the screen name of Ana Paula dos Santos de Carvalho, author of several papers and books about South American butterflies.
Pupae probably form bare, drab chrysalides with a peculiar shape vaguely like dead leaves. I found no photos onlne.
Adolescent butterflies seem to have the ability to pupate through periods of cold or hot weather. Some researchers determined that pupation could be induced by exposing caterpillars and pupae to shorter, cooler days. How, then, do the pupae determine when to eclose? The scientists couldn't say. Simply increasing the temperature did not cause adult butterflies to emerge.
They eclose when they eclose. Females seem to mate as soon as possible in order to spend most of their lives finding good places to lay their eggs.
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