Homerus Swallowtail
Homerus Swallowtail / Caribbean Wildlife Publications
Scientific Name: Pterourus homerus (formerly Papilio homerus)
Range: Jamaica
Habitat: Wet Limestone Forest & Lower Montane Forest
Conservation Status: Endangered
Description
The Homerus Swallowtail is an endangered butterfly endemic to the island of Jamaica. This butterfly is the largest true swallowtail butterfly and the largest butterfly in the Western Hemisphere.Both male and female specimens are similar in appearance but females are generally a bit larger than males. Male specimens have an average wingspan of 113 mm (4.5 inches) and an average forewing of 57 mm whilst female specimen have an average wingspan of 117 mm (4.8 inches) and an average forewing of 59 mm (V. Turland, pers. comm April 5, 2020).
On the dorsal (upper) surface of the Homerus swallowtail, the forewing and hindwings are primarily dark brown to black in colour with a broad yellow discal (central) band stretching across both fore- and hindwings. Powder blue speckled postdiscal (below center) spots and brick red submarginal lunules (crescent shaped marks) can be found on the hindwings.
Dorsal View of Homerus Swallowtail specimen collected in 1887 / Robert Nash
The ventral surface of the hindwing has a more narrow discal band that is darker in colour followed by the same blue postdiscal spots.
Range
The Homerus swallowtail can only be found naturally on the island of Jamaica.
The butterfly was once found in several parishes but is now restricted to two isolated populations in the Cockpit Country and the Blue & Johncrow Mountains.
Map of Jamaica showing the two areas where the Homerus Swallowtail can be found
Habitat
The Homerus Swallowtail inhabits the Wet Limestone Forest of the Cockpit Country and the Lower Montane Forest of the Blue & Johncrow Mountains.
The swallowtail can be found in areas of high elevation and high humidity, usually areas of primary forests with little to no significant human disturbance.
In the Cockpit Country, swallowtail inhabited areas have elevations of 300 m - 780 m with annual rainfall between 190 cm - 380 cm. The areas of the Blue & Johncrow Mtns. are at higher elevations of 610 m - 1070 m with a higher annual rainfall of 250 cm - 700 cm.
Diet
Adult and Larval stages of the Homerus Swallowtail feed on different plants.
Homerus Swallowtail larvae feed on the leaves of Hernandia spp. These host plants are endemic to Jamaica and can be found at elevations. Larvae of the Western population feed on Hernandia jamaicensis whilst larvae of the Eastern population feed on Hernandia catalpilofia.
Adult butterflies are more opportunistic feeders, feeding on the nectar of several flowers. Common flowers visited by the Homerus Swallowtail include Spanish Needle, Lantana sp. and hibiscus.
Behaviour
Homerus swallowtail larvae are primarily nocturnal, feeding at night and resting during the day.
Adult butterflies are most active during the hours between 8:00 am to 4:00 pm and can be found flying about open areas, stopping often to bask in the sun on the leaves of canopy trees or shrubs. During the hot afternoon hours, the swallowtail typically retreats to a cooler area in the shade.
Male Homerus swallowtails display territorial behaviour actively patrolling their territory and chasing away other males or small birds that invade their area.
Breeding
The entire life cycle of the Homerus Swallowtail lasts around 63 -78 days.
This starts with the adult butterfly laying pale green eggs on the host plants, Hernandia spp. The larval stage( approx. 45 days) consists of five instars. Homerus larvae is very sensitive to the environment and requires the high humidity of the forest for successful development.
The larval stage is followed by chrysalis and then emergence of the butterfly. Larvae developing in humidity less than 100% results in butterflies that struggle to open their wings after chrysalis.
Conservation Status
The Homerus Swallowtail is considered to be endangered due to very small populations.
Threats
The major threat affecting the Homerus Swallowtail is habitat degradation and forest fragmentation. Land clearing typically for agriculture (Coffee farming in the Blue & Johncrow Mtns. and cash crops in the Cockpit Country) reduces host plants and the amount of area that the swallowtail can inhabit as well as changes the environmental conditions. This increases the light, temperature and wind in the area and reduces the humidity. A vital factor for successful development during the life cycle.
Another threat to the Homerus Swallowtail is high egg mortality due to parasitism, pathogenesis and predation. Predators include ants, lizards and birds.
A notable threat to the swallowtail is poaching. Poaching was very prevalent in the 70s and the 80s with collectors paying several hundreds of US dollars for intact Homerus Swallowtail specimens.
Protection by the Law
The Homerus Swallowtail was listed as a CITES Appendix I species (endangered species threatened with near extinction)in 1987 prohibiting commercial international trade of the butterfly.
In 1988, the swallowtail became protected under the Jamaican Wildlife Protection Act of 1945.
CITES - Convention of International Trade in Endangered Species of Wild Fauna and Flora