Nectar sources for adult Schaus' Swallowtails include guava (Psidium guajava), cheese shrub (Morinda royoc), and wild coffee (Psychotria nervosa), all of which are white-flowered woody plants (Opler and Krizek 1984). Other reported nectar plants include blue porterweed (Stachytarpheta jamaicensis), sea grape (Coccoloba uvifera), and wild sage (Lantana involucrata) (USFWS 1999)
Schaus' Swallowtail usually flies close to the ground (Brock and Kaufman 2003). In Florida, adults are flying only from late April to early June, rarely July-September (Opler 1992). Males patrol hammock edges and trails for mate, most actively in the morning and late afternoon (Cech and Tudor 2005).
Papilio aristodemus (=Heraclides aristodemus) is a striking butterfly species of the Greater Antilles, with a well studied and highly endangered subspecies, Papilio aristodemus ponceanus, that is endemic to extreme southern Florida. The Florida subspecies was discovered in a hardwood hammock (now destroyed) south of Miami in 1898 by Dr. William Schaus, a physician who was attending soldiers injured in the Spanish-American War (Cech and Tudor 2005). Schaus' Swallowtail was one of the first two invertebrates to receive legal protection under the U.S. Endangered Species Act. It is closely associated with tropical hardwood hammocks, a habitat type that has been decimated by development in South Florida.
The conservation history and status of Schaus' Swallowtail were comprehensively reviewed in 1999 and 2007 by the U.S. Fish & Wildlife Service (USFWS 1999, 2007).
Based on Opler and Krizek Schaus' Swallowtail account (1984): Development from egg to chrysalid takes about 5 to 6 weeks. The egg is pale green and spherical. Young larvae are glistening black, with anterior and posterior white saddlemarks, together with a white patch on each side near the middle of the body. The mature caterpillar has a pure white hood at the posterior end of the body and a series of about six lateral white and yellow patches. The body is otherwise rich brown above and white below. Adult emergence is triggered by rainfall and pupae may pass one or two years before producing adults.
The Schaus' Swallowtail (Papilio aristodemus) is found in extreme southern Florida and the upper Keys, where it is highly endangered, as well as in the Bahamas and Greater Antilles. The distribution of the highly endangered Florida subspecies, Papilio aristodemus ponceanus, has been reviewed by Cech and Tudor (2005) and, in greater detail, by the U.S. Fish & Wildlife Service (1999, 2007). Schaus' Swallowtail was last seen on the Florida mainland in 1924; it was later discovered on Lower Matecumbe Key, but this colony was destroyed by a hurricane in the 1930s. A population of about 1000 individuals was later discovered on the Upper Keys (mainly Key Largo and Elliott Keys), but in 1992 Hurricane Andrew reduced this population by about 90%. This population has subsequently rebounded in Biscayne National Park and has been reintroduced on the Keys and near Miami following a captive breeding program (Cech and Tudor 2005). Consistently occupied habitat occurs on north Key Largo and keys within Biscayne National Park. Biscayne National Park, particularly Elliott Key, constitutes the core of the range (USFWS 2007).
The Schaus' Swallowtail is found almost exclusively in dry tropical hardwood hammocks (dense "islands" of broad-leafed trees that grow on natural rises of only a few inches in elevation) or surrounding scrub (Brock and Kaufman 2003; Cech and Tudor 2005). Hardwood hammocks in Florida are now limited largely to the Upper Keys in Miami-Dade and Monroe Counties.
The Schaus' Swallowtail lays its eggs on plants in the Rutaceae (citrus family), in particular Torchwood (Amyris elemifera) and Wild Lime (Zanthoxylum fagara) in shaded situations; the leaves of these plants are fed on by the developing caterpillar larvae (Opler and Krizek 1984; Brock and Kaufman 2003; Cech and Tudor 2005; FWS 1999).
The Florida subspecies of Schaus' Swallowtail (Papilio aristodemus ponceanus) was listed as "threatened" under the U.S. Endangered Species Act in 1976. As a result of a decline in its numbers and geographic range (Loftus and Kushlan 1984), the U.S. Fish & Wildlife Service reclassified it as endangered in 1984 (FR 49 34501), the status under which it is currently protected by law.
The Schaus' Swallowtail somewhat resembles the far more common Giant Swallowtail (Papilio cresphontes), but the larger Giant Swallowtail has yellow centers on its long hindwing tails (Schaus' has shorter, yellow-edged tails) and yellow bands on the forewing above that form an "X" near the wingtips (Brock and Kaufman 2003; Cech and Tudor 2005). These yellow forewing bands are noticeably broader in the Giant Swallowtail (Opler 1992). Below, Schaus' Swallowtail has a much larger rusty brown patch (Brock and Kaufman 2003; Cech and Tudor 2005). The sexes of Giant swallowtail are similar, but male Schaus' Swallowtails have yellow antennal clubs (the females antennae are all dark).
Wingspan of Schaus' Swallowtail is 92 to 118 mm (Opler 1992).
The taxonomic and nomenclatural history of Schaus' Swallowtail was reviewed by the U.S. Fish & Wildlife Service in the Multi-Species Recovery Plan for South Florida (USFWS 1999). Schaus' Swallowtail was originally described by Schaus in 1911 as a full species, Papilio ponceana, although the author noted the close relationship to forms in Cuba and Haiti. However, beginning just a few years later and up to the present time, the South Florida form has generally been treated as a subspecies (Papilio aristodemus ponceanus) of a more broadly distributed Antillean species (Papilio aristodemus). Opler and Krizek (1984) note that this is one of the few species endemic to the Caribbean that has a distinct subspecies limited to the Florida Keys. Some authors split Papilio into several genera and hence use the name Heraclides aristodemus ponceanus for Schaus' swallowtail. Although the systematics and taxonomy of Papilio aristodemus requires further work, it is possible that the form in Florida should, in fact, be treated as a full species, as it was originally described (USFWS 1999).
Threats to Schaus' Swallowtail include habitat loss from human construction, mosquito spraying and other toxic chemical exposure, road kills, and natural disasters such as hurricanes, droughts, and freezes (USFWS 1999).
Forys et al. (2001) examined the potential risk to the Schaus' swallowtail from invasive red imported fire ants (Solenopsis invicta). This ant is now present in all major habitat types on most or all of the Florida Keys. Red imported fire ants are known to prey on a wide range of other invertebrates and Schaus' Swallowtail eggs, larvae, and pupae may be especially vulnerable because they occur on tree species (torchwood, wild lime) that generally occupy habitat edges where red imported fire ant infestations tend to be the highest. In experiments with eggs, larvae, and pupae of the related and ecologically similar (but far more common) Giant Swallowtail (Papilio cresphontes), all these immature life stages were attacked and consumed by the ants (Forys et al. 2000). As a component of recovery efforts for the Schaus' Swallowtail, Forys et al. propose habitat restoration and possibly other measures to reduce populations of the disturbance-loving fire ants. The authors note that reducing fire ant populations would likely benefit other rare and vulnerable species as well, such as the Key Largo cotton mouse (Peromyscus gossypinus), the Key Largo woodrat (Neotoma floridana smalli), and the Florida tree snail (Liguus fasciatus). Another non-native ant, the Mexican twig ant (Pseudomyrmex mexicanus), may also pose a serious threat to Schaus' Swallowtail (USFWS 2007).
Papilio aristodemus, the Schaus' swallowtail or island swallowtail, is a species of American butterfly in the family Papilionidae. It is found in southern Florida in the United States and throughout the West Indies. It is named in honor of William Schaus.[3]
There are five subspecies:
Schaus' swallowtail has black-brown wings with yellow markings and a broad rusty patch underneath the hindwing.[9] The male's antennae are black with a yellow knob, while the female's antennae are all black. Their forewings have a dull yellow median band from the apex to about midpoint of the inner margin, with a short side branch to costa about one-third the distance from the apex.[10] This species may be confused with the giant swallowtail, but they can be differentiated by the small red patch on the ventral wing (within the small blue band) of the giant swallowtail, which the Schaus' swallowtail doesn't have.[11]
Schaus' swallowtail has a wingspan of 3+1⁄4 by 3+3⁄4 inches (82 by 95 mm).[10]
Torchwood is the primary source of food. Adults have been observed taking nectar from blossoms of guava, cheese shrub, hibiscus and wild coffee. Guava, although an exotic, seemed to be the nectar source preferred by individuals. Schaus' swallowtails will fly some distance from their homes to find blooming guava flowers.[12] Caterpillar host plants are in the family Rutaceae and include hoptree (Ptelea trifoliata), citrus species, sea torchwood (Amyris elemifera), and lime prickly-ash (Zanthoxylum fagara).[13]
In the United States, Schaus's swallowtail is indigenous to the southern tip of Florida. Historically it occurred in tropical hardwood hammock from South Miami to Lower Matecumbe Key, Florida. These butterflies inhabit the hardwood hammocks of the area where they prefer to stay out of direct sunlight. While they inhabit the islands around southern Florida, they are known to live at a relatively high elevation (3.0 to 4.6 meters above sea level), staying away from the tidal waters.[14] Today, it is only found around the Florida Keys, mainly in the islands of Biscayne National Park and Key Largo.[15] It is also found in The Bahamas, Hispaniola (the Dominican Republic and Haiti), the Cayman Islands, Cuba, and possibly Puerto Rico.
Schaus' swallowtails seem to be territorial. Males are seen to patrol females and investigate other butterflies entering their area. Male butterflies have been reported to patrol tree tops as high as 10 feet (3.0 m) on hot afternoons. They also linger in open areas for female Schaus' swallowtails. The flight pattern is usually rapid and unpredictable at about 1 to 2 m off the ground.[16] Research also notes that male Schaus' swallowtail butterflies are remarkably adapted to flight within hardwood hammocks and are able to pick their way among branches and around spider webs. Schaus' swallowtails spend much of their time within hammocks, particularly where sunlight penetrates to give a dappling effect.[17] Tropical hardwood hammocks are the environment for these butterflies which are found in the Florida Keys and the northern shores of the Florida Bay. Consequently, Florida is the place where Schaus' swallowtails live. Unfortunately, with hurricanes and the destruction of these hammock habitats, the Schaus has lost much of its population. These tropical hardwood hammocks are essential for the butterfly’s mating and nectaring activities. The butterfly appears to be diurnal with sightings from as early as 7 am to as late as 7 pm.
Schaus' swallowtail is capable of flying as far as 5.8 miles (9.3 km) a day and travel between the Florida Keys. In 1986, a Schaus' swallowtail butterfly was seen crossing about 360 m from Old Rhodes Key to Swan Key.[18] This observation indicates that these butterflies can travel across open water for a considerable distances among the Upper Keys and may be able to travel to and from the mainland.
Schaus' swallowtail butterflies have a single annual flight season, primarily in May and June, where adults are active; most sightings have been recorded between mid-April and mid-July.[19]: 748 There is only one generation of Schaus' swallowtail butterfly per year and adults are short lived.[20]
Papilio aristodemus produces only one generation per year. This fact is in large part the reason that the Schaus are at high risk of endangerment. The female swallowtail lays pinhead-sized eggs on wild lime between April and June. Up to ten days later, the larvae emerge and after three to four weeks later they mature into caterpillars. These caterpillars can grow up to three inches (76 mm) in length. After the caterpillars mature they then pupate (a pupa is an insect at the immobile non-feeding stage of development between larva and adult, and pupating is when many internal changes occur in the pupa stage) and remain in their chrysalis until the following spring.[21] Some caterpillars hibernate in their chrysalids, and they can remain dormant for up to two years. Before the females can lay the eggs however, they must mate with a male. The male butterflies patrol in tree canopies looking for any receptive females.[22]
The adult emergence of this species is commonly triggered by rainfall. Their primary flight sequences frequently begin in late April to mid-June; however, some adults fly in late July and early September.[22] They have also, over time, developed the unique ability to stop in mid-air and fly backwards in order to avoid their predators, such as birds, lizards, spiders, etc.[23]
Caterpillar hosts include plants in the citrus family (Rutaceae), such as citrus species, hop tree (Ptelea trifoliata), Zanthoxylum species, and torchwood (Amyris elemifera).[22]
S. a. ponceanus was listed as endangered by the United States Fish and Wildlife Service in 1984 due to dramatic declines in numbers and contraction of range. Threats include mosquito control and destruction of its tropical hardwood hammock habitat.[24] Aside from this, they are also known to be susceptible to dramatic weather conditions such as hurricanes and droughts. For instance in 1992, Hurricane Andrew devastated the region and nearly wiped out the entire population of Schaus's swallowtail, leaving only 73 documented individual survivors.[25] It was considered "uncommon and local" on Hispaniola in a 2020 survey (with the Dominican Republic being the only place aside from Florida where records are available), and was considered rare on the Cayman Islands during a report there in 1975.
Captive rearing has proven to be a successful method of maintaining the population of swallowtails. Preemptive planning prior to Hurricane Andrew led to the first mating and pupae production in captivity in 1993.[26] In 2011 only 41 individual butterflies were counted. When the 2012 census resulted in only five, emergency procedures were initialized in June 2012. Up to four of the five, including the presumed only female will be caught and held until they will lay eggs. Those eggs will be removed and bred at the University of Florida McGuire Center for Lepidoptera and Biodiversity. The caught butterflies and those bred from the eggs will be set free inside Biscayne National Park.[27] By June 2013 several larvae and one living female with one egg had been taken in custody.[28] In August the National Park Service announced the spotting of 31 adult butterflies, several female laying eggs and a large number of larvae along with nine adult Papilio andraemon, thought to be extinct in the US, on one of the more remote islands of the national park.[29]
Due to the rapid reproduction cycle of butterflies, the breeding program at the University of Florida resulted with more than a thousand larvae within two years. In June 2014 a first batch of eleven adult females, four males and 308 larvae were released on Elliott Key within Biscayne National Park.[30]
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{{cite journal}}: Cite journal requires |journal= (help) {{cite journal}}: Cite journal requires |journal= (help) {{cite journal}}: Cite journal requires |journal= (help) {{cite journal}}: Cite journal requires |journal= (help) Papilio aristodemus, the Schaus' swallowtail or island swallowtail, is a species of American butterfly in the family Papilionidae. It is found in southern Florida in the United States and throughout the West Indies. It is named in honor of William Schaus.
