What do Genji firefly larvae eat?

The aquatic larvae feed almost exclusively on a freshwater snail called Semisulcospira libertina (kawanina), biting into the soft body and digesting it externally before eating it.

How long do adult Genji fireflies live?

Adults live for only about two to three weeks after emerging, and unlike their larvae, they do not feed during this stage.

Why does flashing pattern differ between regions?

Populations in western Japan flash at roughly two-second intervals while those in eastern Japan flash at about four-second intervals, a well-documented regional difference in this species' courtship signaling.

Genji Fireflyゲンジボタル

Nipponoluciola cruciataNE— Not Evaluated

The Genji firefly is a large firefly endemic to Japan, famous for the synchronized flashing displays of its males over clean, slow-flowing streams in early summer. Its aquatic larvae feed exclusively on freshwater snails, making the species a living indicator of unpolluted water.

Genji Firefly (reference photo) — Photo: Alpsdake / CC BY-SA 4.0 / Source / cropped

Species Data

Classification: Coleoptera / Lampyridae Source
Size: Adult body length around 15 mm (males 10.5–16.5 mm, females 15.0–18.6 mm), a large species among Japanese fireflies
Lifespan: About 1 year from egg to adult; adults do not feed and live only about 2–3 weeks
Diet: Carnivore Larvae feed exclusively on the freshwater snail Semisulcospira found in clear streams, biting into the soft body and dissolving it with digestive fluid; adults essentially do not eat
Activity: Nocturnal (flies and courts at night while glowing)
Distribution: Endemic to Japan, native to Honshu (south of Yokohama-machi, Aomori), Shikoku, and Kyushu along clean streams; introduced populations also exist in Hokkaido and Hachijo-jima. Source
Sources: ja.wikipedia.org en.wikipedia.org

Did You Know?

In 2022, the species was reclassified from the genus Luciola into the newly established genus Nipponoluciola. Source
Males, which have light organs on their sixth and seventh abdominal segments, flash while flying, while flightless females (with a light organ only on the sixth segment) answer with single pulses near the ground; flash intervals differ regionally, roughly two seconds in western Japan and four seconds in eastern Japan. Source

Where to See This Species

Operating facilities registered on this site: Japan 2

Kyoto City ZooKyotoOpened in 1903

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Toyamashifamiri ParkToyamaOpened in 1984

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Conservation Story

Conservation Status

Not Evaluated (NE)

Sources

ja.wikipedia.org

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FAQ

What do Genji firefly larvae eat?: The aquatic larvae feed almost exclusively on a freshwater snail called Semisulcospira libertina (kawanina), biting into the soft body and digesting it externally before eating it. Source
How long do adult Genji fireflies live?: Adults live for only about two to three weeks after emerging, and unlike their larvae, they do not feed during this stage. Source
Why does flashing pattern differ between regions?: Populations in western Japan flash at roughly two-second intervals while those in eastern Japan flash at about four-second intervals, a well-documented regional difference in this species' courtship signaling. Source
How many operating facilities are registered here?: Operating facilities registered on this site: Japan 2 Source

Books & gear

Source: ja.wikipedia.org en.wikipedia.org