- · Grid units represent actual meters (m); human and animals are drawn to the exact same scale with original silhouette aspect ratios preserved.
- · When a size range is recorded (e.g. 1–1.6m), the lower bound is used for scale comparison.
- · Oriental mayfly silhouette: PhyloPic — Nathan Jay Baker · CC0 1.0 (Ephemera danica)
- · Human silhouette: PhyloPic — NASA · Public Domain Mark 1.0
Oriental mayfly
Ephemera orientalis (Oriental mayfly · トウヨウモンカゲロウ)
Not Evaluated (NE) on the IUCN Red List yet.
💡 Everyday Comparisons for Size, Mass & Speed
- 💡 Its body length of 18–22 mm is slightly smaller than the diameter of a Korean 500-won coin (26.5 mm) (Comparison).
- 💡 Because they swarm toward lights at night, the Seoul Metropolitan Government advises minimizing nighttime lighting, installing window screens, and spraying water with a sprayer or hose to knock them off when they cling to building walls.
- 💡 When walking along waterside trails during mass emergences, wearing a mask is recommended. Adults have vestigial mouthparts, so they do not bite and do not transmit germs.
Reference standards: coach bus ~12 m, mid-size car ~4.9 m, compact car ~1 t, basketball hoop 3.05 m, credit card 8.56 cm.
📖 1. Overview
The oriental mayfly is a mayfly that swarms toward lights at night in May and June in riverside cities of Seoul and Gyeonggi-do. Its nymphs grow in clean water of Grade 2 or better.
🦴 2. Anatomy & Morphology
Adults are 18–22 mm in body length, and because their mouthparts are vestigial, they do not bite people.
🔍 3. Ecology & Behavior
Adults appear from May to September, peaking in May and June, and emerge twice in 1 year. The adult lifespan is short, lasting no more than 4–5 days.
🇰🇷 4. Connection to Korea
Because it appears in massive numbers in Seoul (Gangdong, Gwangjin, Songpa, Seongdong, etc.), Gyeonggi-do (Yangpyeong, Namyangju, Hanam, Guri, etc.), and Sejong, the Seoul Metropolitan Government provides response guidelines. The city advises that spraying pesticides indiscriminately kills other organisms as well.
📚 Sources & References
- • IUCN Red List: not evaluated (NE) — cross-checked with the Wikidata conservation-status entry
- • catalogueoflife.org — 6FP7W
- • 국가생물종목록(국립생물자원관) ktsn 120000023934 — https://species.nibr.go.kr/home/mainHome.do?cont_link=009&subMenu=009002&contCd=009002&ktsn=120000023934
- • wikidata.org — Q13577964
- • news.seoul.go.kr — 570183
- • Silhouette: PhyloPic — Nathan Jay Baker · CC0 1.0 (Congeneric silhouette — Ephemera danica)
Recorded dimensions are widely cited representative estimates from public literature and may vary by study or specimen.