🦋 Byasa genestieri

Common Name: Chinese Rose Windmill

Family: Papilionidae (Swallowtail family)

Genus: Byasa

Subfamily: Papilioninae

📍 Distribution:

Found primarily in southern China, particularly in Yunnan and Sichuan provinces.

Also observed in parts of northern Southeast Asia, depending on altitude and habitat.

🌿 Habitat:

Prefers subtropical to montane forests

Common at mid to high elevations (typically 1000–2000 meters above sea level)

Often found gliding gracefully along forest edges, trails, and near water sources

🧬 Description:

Wingspan: Around 90–120 mm

Coloration:

Forewings: Velvet black with faint white markings and soft scales

Hindwings: Deep black with crimson-red spots and a rose-pink flush, contributing to its name "Rose Windmill"

Tail: Hindwings are long-tailed, resembling the blades of a windmill in flight

Body: Black with a few red tufts or patches on the abdomen

🌱 Larval Host Plants:

Believed to feed on Aristolochia species (pipevines), which are known to be toxic to predators

This gives the butterfly a degree of chemical defense, making it unpalatable to birds

🔬 Behavior and Traits:

Flight Pattern: Slow, gliding, and elegant — hence the "windmill" reference

Mimicry: May be involved in Müllerian mimicry with other toxic butterflies like Atrophaneura species

Seasonal Activity: Most active in spring and early summer

🔴 Conservation Status:

Not formally evaluated by the IUCN, but considered rare or localised

Potential threats include:

Deforestation

Habitat fragmentation

Illegal butterfly collecting

🖋️ Name Etymology:

Named after Genestier, a French missionary and naturalist in China

The name reflects both geographic origin and the butterfly’s rose-hued markings

🦋 Visual Highlights

Striking black wings with a distinctive rose-red patch beneath the hindwings.

Long tails on the hindwings, elegantly fanning out during flight.

These photos capture the butterfly feeding and resting—perfect views of its underside details.

🔬 Species Overview

Taxonomic status: Elevated to full species in 2023 by Hu et al., based on genetic (3.38% COI divergence) and genitalia differences from Byasa latreillei .

Subspecies:

B. g. genestieri – found in western and central Yunnan, Sichuan .

B. g. robus – located in southeastern Yunnan, northeastern Laos, and northern Vietnam .

📸 How to Spot It in the Wild

Habitat: Montane forest edges and river valleys, usually at 1,000–2,000 m elevation.

Behavior: Feeds on nectar and moisture from damp ground; slow, gliding flight.

Identification clues:

Velvet-black upperwings.

Beneath hindwings show bold rose-red patches, not seen on B. latreillei or other windmills.

The long, trailing tails reminiscent of a miniature windmill in action.

🧬 Why It Matters

Its recognition as a separate species underscores the biodiversity richness in Southwest China.

Highlights the importance of genetic studies in taxonomy—what looked like a color variant is indeed a distinct species.