Swallowtail Butterfly

Swallowtail butterflies belong to the Papilionidae family and are huge, beautiful butterflies. There are around 550 species in the family. The majority of the species' individuals live in tropical areas. They are, however, not restricted to it and can be found on every continent except Antarctica. Some of the world's largest butterflies belong to this family. Birdwing butterflies, which belong to the genus Ornithoptera and are the world's largest butterfly, are also members of this family. In the image below, some examples of butterflies are shown:

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Characteristics Of Swallowtail Butterfly

Swallowtails have a number of distinguishing characteristics. The papilionidae swallowtail caterpillar, for example, is one of them. On the prothorax of the papilionidae caterpillar is a repugnatorial structure known as the osmeterium. Normally, the osmeterium is concealed. When the larva is threatened, it fills a transverse groove on the back with fluid and then turns it outward.

Some of the swallowtails' hindwings have a forked aspect to them. When the butterfly is resting with its wings wide, it is easy to see. The common term "swallowtail" comes from this forked look. Linnaeus chose the formal name Papilio for the type genus because papilio means "butterfly" in Latin. Linnaeus gave the members of the family the names of Greek figures for some of the genus's special nicknames. Papilio Machaon was created in honour of Machaon, a member of the Asclepius who is also mentioned in the Iliad. Similarly, the Papilio homerus species was named after Homer, the Greek poet.

The key characteristics that differentiate the Papilionidae from the other butterfly families are:

• In swallowtail caterpillars, the osmeterium is a forked, fleshy eversible organ present in the prothoracic segment.

• The second anal vein, 2A, in swallowtails extends up to the wing border and does not connect with the first anal vein, 1A. In other butterfly families, these veins are united, and 2A does not reach the wing border.

• The cervix's sclerites (membranous neck between the head and the thorax) are united beneath the neck, where the head-movement muscles are fixed. 

The Subfamilies of Swallowtails

Extant swallowtail genera are usually divided into three subfamilies. Baronia, Parnassiinae, and Papilioninae are the three families. The latter two are subdivided further into tribes. Apart from morphological traits, the choices of food plants and the ecological lifestyle of swallowtail species will represent the phylogeny and categorization.

Baronia

The Baronia are a monotypic subfamily of the Baronia. They are usually confined to a tiny area of Mexico. They are considered the subfamilies' most primitive members. The current species Baronia brevicornis is believed to be a surviving species. Pra Papilio, a fossil taxon, shares certain characteristics with it. Baronia is the only papilionidae species that feed on Acacia plants (family Leguminosae).

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Parnassiinae

The Parnassiinae are an entirely Holarctic butterfly subfamily. Mountain ecosystems are home to the vast majority of species, primarily Parnassius. Other habitats where Parnassiinines can be found include "dry deserts (Hypermnestra), damp woodlands (Luehdorfia), and even lowland meadows (Zerynthia)". Parnassiini, Zerynthiini, and Luehdorfiini are the known tribes in the Parnassiinae.

Hypermnestra, a genus mostly restricted to Central Asia, and Parnassius (the Apollos), a separate group of several species, all of which are alpine and capable of living at high altitudes, make up the tribe Parnassiini. On their hindwings, most Parnassius feature two tiny crimson dots. The genera Archon of Asia minor and Luehdorfia of China and Japan belong to the Luehdorfia tribe. The third tribe, Zerynthiini, has kept the archetypal papilionidae feeding plant, the lowland vine Aristolochia, while the other two tribes have evolved to shift their food plants. Sericinus, Bhutanitis, Zerynthia, and Allancastria are the four genera that make up Zerynthia.

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Image: Mountain Apollo, scientifically known as the Parnassius ApolloPapilioninae

The Papilionidae is divided into four tribes: Lepto Circini, Teinopalpini, Troidini, and Papilionini.

Praepapilioninae

An extra subfamily, Praepapilioninae, consists of two extinct butterfly species, each reported from single fossils discovered in a middle Eocene deposit in Colorado, United States (Durden and Rose, 1978).

The Evolution Of The Swallowtail Butterflies

The monophyletic status of the Papilioninae subfamily is now widely accepted. There are roughly 225 species of swallowtail butterflies in the nominate tribe Papilionidae, and studies on their host plant coevolution and phylogeny have been conducted. The validity of old morphological classifications was also discovered since they formed clusters. Species that employ Rutaceae as a host plant were divided into two categories, corresponding to Old World and American taxa. Another cluster of Lauraceae and Magnoliaceae-feeding taxa was discovered, which contains both Asian and American taxa.

According to morphological research, the Parnassians, like the Papilionidae, were thought to be monophyletic, but current studies based on both morphological and molecular traits reveal that this is not the case. Based on molecular investigations, the genera Parnassius and Hypermnestra were discovered to be extremely similar and are now regarded to be members of the Parnassian tribe. The two taxa, Archon and Luehdorfia, were discovered to be closely linked through examination of nuclear and mitochondrial DNA, and have since been merged into the tribe Luehdorfia, despite the fact that they have no morphological resemblance.

The single representative species of the Baronia subfamily is Baronia brevicornis. They are the only members of the family that employ Fabaceae (Leguminosae) as larval host plants. The Baronninae and the extinct subfamily Praepapilioninae are traditionally thought to be the most primitive subfamilies and sisters to the rest of the swallowtails since they share numerous outward features. According to a recent study, the Baronia is closely connected to only the Parnassians, while Pray Papilio is closely related to only the Papilionini, and neither group is sister to the rest of the swallowtails.

Where Are They Found?

There were 552 extant species discovered as of January 2005, with populations spanning tropical and temperate climes. Various species exist at altitudes ranging from sea level to high mountains, including the majority of Parnassius species. The majority of swallowtail species and diversity can be found in the tropics and subtropics, primarily in Southeast Asia, between 20°N and 20°S, and between 20°N and 40°N in East Asia. Only 12 species have been identified in Europe, with Papilio Machaon being the only one found in the UK. In North America, there are 40 species, including some tropical species and Parnassius.

The Siberian Apollo (Parnassius arcticus) is the world's northernmost swallowtail, located in northeastern Yakutia at heights of 1500 metres above sea level. Various Apollo species, such as the Parnassius epaphus, have been discovered at altitudes of 6,000 metres above sea level in the Himalayas.

What Do They Eat?

Swallowtail caterpillars eat a wide variety of plants, with the majority of them belonging to one of five plant families: Aristolochiaceae, Annonaceae, Lauraceae, Umbelliferae (Apiaceae), and Rutaceae. The caterpillars sequester aristolochic acid by consuming some of these toxic plants, rendering both the caterpillars and butterflies toxic and thereby protecting them from predators. For defence against predators, the Parnassius smintheus sequesters sarmentosin from its host plant Sedum lanceolatum. The Zerynthiini (Parnassiinae), Luehdorfiini (Parnassiinae), and Troidini (Papilioninae) swallowtail tribes nearly exclusively employ the Aristolochiaceae family as a host plant.

In the wild, the eastern black swallowtail's primary host plant is Queen Anne's lace. The black swallowtail also depends on carrots, parsley, dill, and fennel from gardens as their food source. 

Adult swallowtails sip nectar, but also mud and sometimes manure.

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Image: Very Rare Swallowtail Butterfly, Iphiclides PodaliriusLife-Cycle Of Swallowtail Butterfly

According to Bingham (1905), the following are extensive descriptions of morphological traits of the Papilionidae, with the images being of the Giant Swallowtail butterfly, Papilio cresphontes:

Egg: "Dome-shaped, smooth or obliquely facetted, not as tall as wide, leathery, opaque." (Doherty.)

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Image: Egg of Giant Swallowtail Butterfly, Papilio Cresphontes

Larva: On the dorsum, stout, smooth, or with a succession of fleshy tubercles; on the fourth segment, a raised fleshy protuberance (the so-called hood or crest). The second segment features a transverse aperture through which the larva can protrude at will, as well as an erect, forked, glandular fleshy organ that has a strong, penetrating, and slightly disagreeable odour.

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Image: Larva of Giant Swallowtail, Papilio cresphontes

Pupa: The shape varies, but it's usually curved rearward. It is angulated, with a rounded or truncated head and a smooth or tuberculate back of the abdomen. It is joined to the body via the tail, which is generally perpendicular and has a silky girth around the midsection. The pupa is laid in a loose silken web between leaves in Parnassius.

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Image: Pupa of Giant swallowtail butterfly, Papilio cresphontes

Imago: Wings come in a wide variety of shapes. A tail on the hindwing is fairly common. It can be slender or broad and spatulate, but it is invariably an extension of the termen at vein 4. The termen of the hindwing in one genus, Armandia, is extended into tails at the apices of veins 2 and 3 as well as vein 4. Except in the aberrant genera Parnassius and Hypermnestra, the forewing has all 12 veins as well as a small internal vein, vein 1 a, that always ends on the dorsal border.

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Image: Imago of giant swallowtail butterfly, Papilio cresphontes

Specialized Adaptations of Swallowtail Butterflies

Swallowtail butterflies engage in Batesian mimicry, a defence mechanism in which the butterflies' appearance closely resembles that of undesirable species. Swallowtails are unlike many other creatures that mimic. The female-limited polymorphism for Batesian mimicry exists in the tiger swallowtail butterfly and tiger swallowtail caterpillar (Papilio glaucus), while others, such as the Canadian tiger swallowtail (Papilio Canadensis), do not. 

Red-winged blackbirds, Pennsylvania fireflies, five-lined skinks, green darners, goldenrod spiders, Chinese mantis, fiery searchers, and striped skunks are among the predators.

Some species have individuals who are not entirely alike in appearance. Y-linkage, for example, affects whether females of Papilio glaucus (eastern tiger butterflies) are wild-type (yellow and black) or melanic (dark melanin replaces the yellow background). Melanism is governed by a single gene that regulates the amount of dopamine in the body, resulting in a hereditary difference. The enzyme BAS is repressed, which helps dopamine produce the yellow colouring that is normally found on the wings' background. The butterfly appears mostly black (the melanic version) without the pigmentation and is a Batesian imitation of Battus philenor, the pipevine swallowtail. There is also Papilio glaucus that isn’t completely black; some have a "sooty" appearance and are temperature sensitive.

The geographical distribution and abundance of its mimic, the Battus philenor, whose wing colour fluctuates depending on its geographical location, determine the distinct polymorphisms (wild-type, melanic, and the sooty intermediate). The background wing colour of the Papilio glaucus must match that of the B. philenor residing in the same regional area in order for predators to mistake it for the B. philenor. The relative abundance of melanic females in the southeastern United States has been observed to connect spatially with B. philenor, according to studies.

Only a small percentage of swallowtails engage in mimicking. Whether one or both sexes are mimetic, and whether the mimicry is monomorphic or polymorphic, varies by species. Female-limited polymorphism, in which only the females of a species are mimetic and polymorphic, often emulating different, distantly related aposematic butterflies, has gotten a lot of attention. Females of Papilio Dardanus, the African swallowtail butterfly, have three different morphs for wing colour pattern: a black-and-white pattern for Batesian mimicry, a black-and-yellow pattern that resembles the species' males, and a pattern with orange patches that resembles the species' elderly males. Given that predators attack males of the species who lack Batesian mimicry far more frequently than females, it's unclear why females would exhibit the non-mimetic wing pattern, which would appear to impair their fitness relative to the mimicry version. Batesian mimicry is also seen in the pipevine swallowtail.

The pseudosexual selection hypothesis and the male avoidance hypothesis are two of the most notable hypotheses regarding this occurrence. Male butterflies aggressively attacked male-looking females, then mellowed their conduct into sexual behaviour once they were close enough to identify them as females, according to the pseudosexual theory. Female butterflies disguise themselves to avoid male harassment, according to the male avoidance hypothesis, because courtship can be dangerous, time-consuming, and attract predators.

Male responses to females of various morphologies were studied, and it was discovered that males consistently preferred Batesian mimics, followed by black and yellow, and finally the morph with orange patches. The scientists concluded that frequency-dependent selection resulted in equal success for all three alternative strategies: the Batesian females faced the fewest predators but lost the most fitness due to sexual harassment, while the other two-faced less sexual harassment but lost fitness due to predator attacks.

Reproduction and Caring of Swallowtail Butterflies

Male Parnassines produce a glue-like substance after mating that is used to close the female genital opening and prevent other males from mating with her. Individual eggs are laid on the undersides of their feeding plants' leaves. Once the eggs have been laid, there is no parental involvement. The cremaster normally attaches the pupae to the substrate, but with the head held up by a silk girdle. The Apollos, on the other hand, pupate in ground debris and construct a loose cocoon. Winters in temperate climates are spent in a pupal diapause stage.

Cultural Aspects of Swallowtail Butterfly

Butterfly collectors have been drawn to swallowtail butterflies because they are huge, colourful, and beautiful. Birdwing butterflies, the largest of them, are especially sought for and are raised at butterfly farms to serve collectors. Many members of the family feed as larvae on plants in the Rutaceae family, which includes citrus. Some of these beautiful insects have become pests in citrus groves.

Oregon's state insect is the Oregon swallowtail. The eastern tiger butterfly of tiger butterflies family Virginia's state bug and Georgia, Delaware, and South Carolina's state butterfly. Oklahoma's state butterfly is the black swallowtail butterfly.