The Genji-botaru firefly is a designated natural monument in Tatsuno due to the town's historical efforts to restore their habitat.
Firefly larvae are aquatic and require high-water quality, making the clean flow of the Matsuo River vital to the park's success.
The peak of the firefly emergence typically spans only a two-week window in June.
Tatsuno town has successfully implemented light-restriction protocols in the park to ensure firefly mating patterns are not disturbed by artificial sources.
Tatsuno Hotarudoyo Park is a nature reserve in Nagano Prefecture specifically managed to preserve the habitat of Genji-botaru fireflies. The park borders the Matsuo River, which serves as a primary breeding ground for these bioluminescent insects. During the peak season in June, the park hosts the Tatsuno Firefly Festival, which draws large crowds to observe the synchronized glowing displays. The park features walking paths, observation decks, and educational displays detailing the life cycle of the local fireflies. It serves as a central hub for the town's conservation efforts to maintain water quality and vegetation suitable for the species. Visitors can access various wooded areas and riverside platforms designed to minimize light pollution and human disruption during observation.
The wooden observation bridge overlooking the Matsuo River.
Wear dark-colored clothing to avoid attracting mosquitoes and to help you blend into the surroundings while watching fireflies.
Bring a flashlight, but cover the lens with red cellophane, as red light is less disruptive to fireflies than white light.
Remain silent and minimize movement near the riverbanks after dark to increase the likelihood of fireflies landing nearby.
Visiting outside of the June firefly season, as the park is primarily a dormant ecological site the rest of the year.
The park is most active and accessible during the firefly festival in mid-June; access to certain river-viewing areas may be restricted during other seasons.
Do not use flash photography, as it disrupts the fireflies' mating signals; refrain from using insect repellent near the water.
