Genji firefly
Nipponoluciola cruciata
Also called: Genji-botaru, Luciola cruciata
At a glance
- Flash
- Slow, bright green flashes, every two to four seconds depending on the region, often in step
- Habitat
- Clean streams and ditches with snails, and the plants along their banks
- Range
- Japan, except Hokkaido and Okinawa
- Season
- May to July, most of all in June
- Size
- Males 10.5–16.5 mm, females up to about 18.6 mm
- When active
- The first hours after dark
Overview
The genji-botaru is the firefly of Japanese summer festivals. Its name may come from The Tale of Genji, or from the Genji clan, who won the Genpei War in the 12th century. Its smaller cousin, the heike-botaru, is named after the clan that lost.
The larvae live underwater in small streams and ditches with mud or pebbles on the bottom. They cannot swim, so they crawl along the bed hunting freshwater snails. After more than a year they leave the water to pupate in the soil, and the adults come out around June. The adults live less than three weeks and do not eat.
Flying males tend to flash in step with each other. The rhythm changes across Japan: about every two seconds in the west and about every four seconds in the north.
Sightings logged here
168 sightings of this species have been logged on Alitaptap.
When they have been seen
| January | February | March | April | May | June | July | August | September | October | November | December |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 1 | 2 | 2 | 31 | 110 | 14 | 2 | 1 | 1 | 1 | 3 |
Most reported in June.
65% of these 168 records were made in June. None has been logged in January yet.
This shows when 168 records were made, not when fireflies fly. A place people only visit in one season looks seasonal for that reason alone, so treat a thin month as “nobody looked” rather than “nothing there”.
Where people saw it
- Karuizawa, Japan
- Minookoen, Osaka 562-0002日本
- Sogabechotera, Japan
- Minoo, Japan
- Tottori, Japan
- Fushimi, Japan
Where and when it has been seen
| Place | Date | Source |
|---|---|---|
| 35.27, 134.32 | iNaturalist → | |
| 35.38, 135.88 | iNaturalist → | |
| Karuizawa, Japan | iNaturalist → | |
| 38.31, 140.44 | iNaturalist → | |
| 34.85, 135.47 | iNaturalist → | |
| 34.84, 135.48 | iNaturalist → | |
| Minookoen, Osaka 562-0002日本 | iNaturalist → | |
| 35.46, 134.25 | iNaturalist → | |
| 35.46, 134.25 | iNaturalist → | |
| Sogabechotera, Japan | iNaturalist → | |
| 35.67, 139.28 | iNaturalist → | |
| 35.67, 139.28 | iNaturalist → | |
| Minoo, Japan | iNaturalist → | |
| 38.25, 140.86 | iNaturalist → | |
| Tottori, Japan | iNaturalist → | |
| Fushimi, Japan | iNaturalist → | |
| 35.45, 134.25 | iNaturalist → | |
| 35.45, 134.25 | iNaturalist → | |
| 35.20, 135.92 | iNaturalist → | |
| 33.60, 130.21 | iNaturalist → |
Showing the 20 most recent of 168 records.
Browse all sightings →How to identify
Large fireflies with slow, bright flashes over a stream in Japan in early summer. The smaller heike-botaru flashes faster and lives in rice paddies and ponds.
Conservation
It depends on clean, flowing water and the snails that live in it. Concrete channels, pollution and bright lights have pushed it out of many places.
Sources & further reading
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