This area was designated as Japan's only special national treasure as a habitat for fireflies.
The body length of a male firefly is 15mm, with the female being larger at 18mm. It takes approx. 1 year to grow from egg to final imago form, and the major part of their lives is spent in water. After becoming an adult, fireflies live for only as short as approx. 1 to 2 weeks.
Fireflies flit about 3 times during the night. Fireflies fly about for the 1st time from 8:00PM to 9:00PM, for the 2nd time around 11:00PM, and then for the 3rd time around 2:00AM. Female fireflies start to fly from the grass as the night goes on.