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).
