Ulysses Swallowtail

Physical Characteristics

The Ulysses Swallowtail (Papilio ulysses) is one of the most iconic butterflies of Australia and Papua New Guinea, admired for its electric blue coloration, broad wings, and powerful flight. It is a large member of the swallowtail family (Papilionidae), often considered a symbol of tropical elegance.

Coloration (Upperside):

• The forewings and hindwings display an iridescent, metallic blue that appears almost neon in sunlight

• Blue areas are bordered with deep black margins, creating a bold contrast

• The amount of blue varies slightly between subspecies and individuals

Coloration (Underside):

• The underside is mottled brown to black, providing camouflage when the butterfly is at rest with closed wings

• The forewing undersides may include white or pale blue streaks

Wings:

• Wings are broad, slightly scalloped, and curved at the edges

• Hindwings possess short, rounded tails—a swallowtail signature

• Wingspan: 4.7 to 5.5 in (12 to 14 cm), making it one of the largest butterflies in its native range

Body and Antennae:

• The body is robust and dark brown to black, with some blue scaling near the thorax

• Antennae are long, slender, and clubbed, typical of swallowtails

Flight Pattern:

• Flight is fast, strong, and fluttery, often high in the canopy but descending to feed

• The blue flashes are highly visible in sunlight but vanish when wings close, aiding in escape from predators

Sexual Dimorphism:

• Minimal external differences; males and females are similarly colored

• Females may be slightly larger and may have more rounded wings

Structural Note:

• The intense blue is not due to pigment but to structural coloration—microscopic wing scales that reflect light in specific wavelengths

The Ulysses Swallowtail’s electric blue shimmer, powerful wings, and graceful flight make it one of the most photographed and admired butterflies in Australasia.

Reproduction

The Ulysses Swallowtail has a well-adapted reproductive cycle for tropical environments, with a strong reliance on specific larval host trees and bright coloration that plays a role in mate attraction. It follows a complete metamorphosis: egg, larva, pupa, and adult.

1. Mating Behavior:

• Males are highly visual and territorial, often seen patrolling sunlit forest clearings and tree canopies for females

• The bright blue iridescence of the male is believed to be a key courtship signal, visible from long distances

• Courtship involves spiral flights and short chases before copulation

2. Oviposition (Egg Laying):

• Females lay single pale green eggs on the young leaves of larval host plants, especially:

  • Melicope elleryana (Pink Flowered Doughwood)

  • Other Melicope and Euodia species in the Rutaceae family

• Eggs are round and smooth, hatching in 4 to 6 days

3. Larval Stage (Caterpillar):

• The caterpillar is bright green with yellowish spots and has a smooth body with a slightly swollen thorax

• Early instars may mimic bird droppings for camouflage

• The larva possesses an osmeterium, a forked orange gland that emits a foul odor when threatened

• The larval stage lasts 2 to 3 weeks, depending on temperature and food availability

4. Pupal Stage (Chrysalis):

• The pupa is green or brown, angular, and attaches upright to a branch or leaf stem with a silk pad and girdle

• Pupation lasts 10 to 14 days, but can extend if weather conditions are suboptimal

5. Adult Emergence and Maturity:

• Adults emerge with soft wings, which expand and harden within an hour

• Sexual maturity is reached within 2 to 4 days after emergence

• Females begin searching for host plants shortly after mating

Breeding Frequency:

• The Ulysses Swallowtail is multivoltine, producing several generations per year in warm climates with continuous vegetation growth

• Breeding may peak after rains when larval host plants are flush with new growth

The Ulysses Swallowtail’s reproductive success is linked to its bright visual signals, specialized host plants, and the ability to thrive year-round in tropical rainforest habitats.

Lifespan

The Ulysses Swallowtail has a moderate lifespan typical of large tropical swallowtails, supported by year-round breeding in warm climates and strong adult flight capabilities. Its vibrant coloration and fast reflexes help it survive despite being a high-visibility species.

Lifespan in the Wild:

• Egg Stage: 4 to 6 days

• Larval Stage (Caterpillar): 2 to 3 weeks

• Pupal Stage (Chrysalis): 10 to 14 days

• Adult Butterfly: 3 to 5 weeks, depending on weather, food availability, and predation

Total life cycle duration: Approximately 5 to 7 weeks from egg to adult death under favorable tropical conditions.

Generations Per Year:
The Ulysses Swallowtail is multivoltine, producing several overlapping generations each year, especially in consistently warm and moist environments such as:

• Northeastern Australia (Queensland)

• Papua New Guinea

• Solomon Islands

Lifespan in Captivity:

• Adults in butterfly houses may live slightly longer—up to 6 weeks—due to consistent food sources and protection from predators

• Captive conditions must include flowering nectar plants and access to host plants for breeding

Threats to Longevity:

• Predation by birds, lizards, and spiders, especially during the egg and larval stages

• Habitat loss, particularly the removal of larval host trees like Melicope elleryana

• Extreme weather events (droughts, cyclones) that disrupt breeding or food supply

• Human collection and handling, which may shorten lifespan in exhibition environments

The Ulysses Swallowtail’s moderate lifespan is balanced by its high reproductive turnover, visual defense mechanisms, and ability to rapidly repopulate local areas with multiple broods per year.

Eating Habits

The Ulysses Swallowtail is a nectar-feeding butterfly with a highly visual foraging strategy. Its bright coloration and fast, deliberate flight help it locate floral resources in tropical rainforests while avoiding predators.

Larval Diet (Caterpillar Stage):

• Caterpillars feed exclusively on host plants in the Rutaceae family, primarily:

  • Melicope elleryana (Pink-flowered Doughwood)

  • Euodia and other Melicope species

• Larvae consume young, tender leaves, gradually moving to larger foliage as they grow

• Host plants contain chemical compounds that provide mild toxicity and defense to larvae

Pupal Stage:

• The chrysalis does not feed. It remains suspended in place while undergoing metamorphosis

Adult Diet (Butterfly Stage):

• Adults feed on nectar from a wide variety of flowering plants, especially those with:

  • Tubular or open blossoms in bright colors like pink, red, and orange

  • Sufficient nectar reserves to fuel their high-energy flight

• Common nectar sources include:

  • Lantana camara

  • Hibiscus spp.

  • Bougainvillea

  • Ixora

  • Buddleja (Butterfly Bush)

Feeding Behavior:

• Adults use a long, coiled proboscis to sip nectar while hovering or perching briefly

• Foraging occurs during daylight hours, especially in sunny breaks within rainforests

• The butterflies frequently return to nectar-rich flowering trees, often near forest edges or clearings

Visual Feeding Cues:

• Ulysses Swallowtails are strongly attracted to blue and pink flowers, often using color recognition from flight

• Males also patrol these areas while seeking mates, combining feeding and courtship behavior

The Ulysses Swallowtail’s nectar-feeding habits support its powerful flight and territorial displays, while the caterpillar’s host-specific herbivory ensures strong larval development and continuity of the species across generations.

Uniqueness

The Ulysses Swallowtail is one of the most visually iconic butterflies of the Australasian tropics, celebrated for its brilliant blue iridescence, high-speed flight, and its role as a symbol of natural beauty in Australia. Its combination of show-stopping appearance and specialized behavior makes it a standout species both biologically and culturally.

Iridescent Electric Blue Wings:
The butterfly’s upper wings shimmer with metallic, structural blue, a result of microscopic scales that reflect and refract light. This makes the butterfly highly visible when in motion, yet nearly invisible at rest when the wings close to reveal the brown, cryptic underside.

Flash Defense Mechanism:
The strong contrast between the bright blue upperside and dull underside provides a unique flash-and-hide defense: predators spot a flash of blue, but when the butterfly lands and folds its wings, it seems to disappear into the background.

High-Speed, Canopy-Level Flight:
Ulysses Swallowtails are known for their fast, purposeful, and fluttery flight, especially in tropical forest canopies. While many butterflies drift lazily near the ground, this species often patrols treetops, diving down to feed or court.

Cultural Symbol in Australia:
In Queensland, the Ulysses Swallowtail is widely recognized as a symbol of tropical biodiversity and ecotourism appeal. It features in regional branding, signage, and butterfly house exhibits, often called the “Blue Mountain Butterfly.”

Territorial Males with Strong Visual Cues:
Males are strongly attracted to blue-colored objects, including signs, clothing, or artificial flowers. This color recognition likely evolved to help them locate mates and nectar sources in a visually dense forest environment.

Specialized Larval Host Plants:
The caterpillars feed almost exclusively on trees in the Rutaceae family, including Melicope elleryana—a native flowering tree. Conservation of these host trees is critical to sustaining wild populations.

Photogenic and Ecotourism-Friendly:
Due to its slow glides, large size, and electric coloration, the Ulysses Swallowtail is a favorite of nature photographers and butterfly watchers, and it is often used in butterfly house displays around the world.

The Ulysses Swallowtail’s dazzling color, fast flight, and symbolic role in Australian nature tourism make it not only biologically distinctive but also culturally cherished—a true emblem of tropical beauty.