Is Oberthuer's Kite Swallowtail really a distinct species? It's rare, if it is. Three specimens have been found in two distinct places, Honduras and Mexico. Very little about Eurytides, or Neographium, Protographium, or Protesilaus oberthueri, has been published. If it is a distinct species, it's very similar to E. (or N. or P.) philolaus, of which it's often considered a subspecies. This web site will compromise. We'll consider oberthueri and philolaus together in one post. For those using older lists in alphabetical order, we'll come back to orabilis next week.
Photo by SilvanoLG, documenting that philolaus form large flocks.
In 1906, Walter Rothschild discussed the perplexity entomologists were in about the species of Zebra Swallowtails. He thought ten species, including celadon, arcesilaus, epidaus, and bellerophon, might eventually turn out to be subspecies of Zebras, and discussed them as "the marcellus group." What he called Papilio philolaus was in that group, the Dark Zebra. Its antennae are black rather than amber, but may be "feebly tawny at base." Its legs are pale green. Its tiny claws are shorter than the Zebra's. Its wings usually show black and pale green stripes in patterns slightly different from the Zebra's; some females are almost all black and show only faint shadows of these stripes.
Photo by Juancarlosgarciamorales1, showing a typical male philolaus looking very similar to a large, dark, Southern Zebra Swallowtail. (Wingspans range between 3 and 4 inches.)
The upper wings can be almost entirely black.
Photo by Escalante-Pasos.
Oberthueri differed from philolaus in having a translucent stripe, as well as white stripes. The dark stripes were paler or more translucent, also, and the hind wings narrower. The drawing labelled "Oberthueri" in Rothschild's Novitates Zoologicae looks remarkably like marcellus.
So does the museum specimen here:
Photo from InsectNet.
Some think oberthueri was a natural hybrid between philolaus and one of the paler Kites, probably agesilaus. Many hybrids are "mule" species in which disparate genes inhibit reproduction. That would explain why more oberthueri have not been found. "Mules" recur predictably if and when the same species hybridize; they don't mate with each other and produce a second generation of "mules." Biolib lists oberthueri as a hybrid:
But philolaus is fairly abundant. Usually considered a Mexican species, it strays north into the Western States every few years and is found on checklists for southern California and Arizona butterfly watching. In southern Texas it can even be considered native.
Its variability, and the family resemblance of all the Kites, have given philolaus many names. Apart from the ongoing discussion of whether the genus name ought to be Papilio (everyone now agrees that that genus was overcrowded), Eurytides, Protographium, Neographium, or maybe Protesilaus, people have called the species or various possible subspecies ajax, felicis, niger, nigrescens, philenora, plaesiolaus, scheba, vazquezae, xanthicles, and xanticles. Currently xanticles, the southern type, is recognized as a subspecies.
Photo by Sabrewing, explaining that philenora business. Well, yes, if she didn't have those long tails, and had that blue gloss on her wings, she would look a bit like Battus philenor. The name philenor or philenora is traced to the Greek words for "loves her husband." Butterflies don't form pair bonds but she undoubtedly cares as much about her mate as any other butterfly does. (If butterflies, male or female, get more than one opportunity to mate, they will, and the older ones who have mated before will look for young partners who have not.)
She might look enough like B. philenor to fool a bird, though. The dark Southern subspecies, with yellow spots on the upper wings, are the form for which the name scheba was proposed. Bible stories were generally considered too "sacred" to be included in the general category of ancient literature, but Belqis, the Queen of Sheba, who made a state visit to Suleiman Bin Daoud of Israel, was a character in Arab and African literature too. When male Swallowtails congregate at puddles, their social groups, or leks, are visited by females. Female butterflies are not there to negotiate terms of international trade, but then, male writers have always fantasized that that wasn't why Belqis visited Suleiman either.
Xanthicles is one of those European names that combine two words more or less randomly, without regard to any meaning the resulting phrase has. Xanthos is the Greek word for light-colored, blond, yellow, dun; one web site points out that light brown and red hair were also considered "light-colored." Cleis is the word for fame and glory. The name Xanthicles or Xanticles appears in ancient literature, though not as the name of a major character in any story. Eurytides (or Protographium) philolaus xanticles has a yellow color, rather than blue-green, in its light-colored sections.
Photo by Andreshs.
Bright yellow color is the distinguishing feature of the subspecies xanthicles, but it fades quickly. Older butterflies and museum specimens are brown and tan, rather than black and yellow. The yellow color may shade to off-white or pale green on the underside of the wings.
Photo by camilojotage. Though this large mixed flock of Swallowtail and other butterflies is not unusual, its clear focus is, because philolaus and other swallowtails fan their wings almost constantly, even while sipping water from wet sand.
Why do they flutter so much? To cool off? Possibly, though other butterflies survive without spending their energy this way. To confuse predators? Probably, though, again, other butterflies get by without this behavior. To preserve inter-butterfly space at a crowded puddle? Likely, though they do it when they're not crowded. To advertise themselves, scenting the air with an odor humans don't seem to notice, giving females an idea of how many of the males at the puddle are ready to mate? Possibly, though female Swallowtails, most of whom are ready to start unloading their eggs when they crawl out of their chrysalides, would probably find males and wait for them to mature anyway. To make themselves more of a challenge and thus more interesting to photographers? Probably not, although the behavior has that effect, and it may benefit the butterflies. The true answer may well be "because they can."
Video of a large flock, fluttering, while wind rustles nearby plants:
Though not economically important, it is popular enough to have appeared on postage:
Photo from Avionstamps.com.
The few photos available of couples of this species show that they can mate face to face, each clinging to one side of a twig. Females then flit off to the bushes to lay eggs, and males return to their leks and wait to another chance to mate.
Caterpillars have that humpbacked Swallowtail look, the fleshy "horns" of the forked osmeterium tucked away on their upper backs. They have pairs of white blotches that can form stripes running for part or all of the length of a black or green body.
Photo by Thibaudaronson.
Photo by Karla_bal30.
Photo by Tristan_menant-leclercq, documenting their tidy habit of eating their outgrown skins. Various arrangements of black, white, and olive green patches are possible for this caterpillar. The overall effect seems to be in the look-like-a-bird-dropping category of survival strategies for caterpillars.
Caterpillars eat shrubs in the Annonaceae family, the family that includes North American pawpaw trees. How many different species of leaves they can eat, or how their selections affect their looks, is not documented.
Neither egg nor chrysalis photos are available online at the time of writing, though Inaturalist has some clear long-range photos of females flitting among host plants and palpating leaves.
The life cycle of these butterflies has not been fully documented. Adults fly between March and September, and are most often seen in May.
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