In Japanese, the word “hotaru” means firefly. These insects have long been part of the Japanese culture, often appearing in myths and artwork. They are revered because they represent the warmth of love, and their nocturnal lightshows suggest otherworldly existence. However, the fireflies of Japan, and around the globe, are disappearing.

The Zoological Lighting Institute has produced a video called “Brilliant Darkness: Hotaru in the Night,” that delves into the plight of the firefly. Research has pinpointed human-generated light pollution as a primary cause of the decrease in firefly populations. Most fireflies need darkness in order to flash (there are a few species that are active during the day, but most are active at night). This flashing attracts females of the species to the males. As humans have expanded their range and built more cities and towns, the once dark areas of forests and fields are now flooded with light. The fireflies do not flash, so reproduction does not occur.

The filmmakers divide the video into three major segments. The first, called “Brilliant Darkness,” includes a series of interviews with researchers in America and Japan that address how and why firefly populations are dwindling and what efforts are being made to increase their numbers. For example, one of the scientists interviewed works on creating energy-efficient lighting that does not interfere with firefly mating rituals. The second segment of the video is called “Light of the Genji.” Genji are a type of firefly in Japan. This segment explores the life cycle of the firefly and assays a few of their different species. It describes how there are over 2,000 different species of fireflies, and some only live for about two weeks! The final segment of the film is a non-captioned viewing of fireflies in their natural habitats. There is no dialog, just moving images of fireflies. This part was reminiscent of the old fireplace videos from the 1980s that people would put on their televisions around Christmas time—exciting for a few minutes, but after that, quite boring.

The take-home message from this film is that human activities have a dramatic effect on the population size of fireflies around the world. The video does a nice job of showing these connections and their overall impact. The narrative offers some suggestions on how to fix the problem with declining firefly populations, but most sound superficial and limited. On occasion the primary language of the film switches to Japanese with English subtitles; some students may find that distracting.

Overall, this is a good film that would be appropriate for grades 6 and up. It covers NGSS Disciplinary Core Ideas LS2.A (Interdependent Relationships in Ecosystems), LS2.C (Ecosystem Dynamics, Functioning, and Resilience), and LS4.D (Biodiversity and Humans). It also addresses two Cross-Cutting Concepts: Cause and Effect, and Stability and Change. The film might serve an environmental science class investigating human impacts on the ecosystem. Instructors could allow students to watch the video and prompt them to generate unique solutions that might help save the fireflies.

REMY DOU taught high school life science for eight years before becoming an Albert Einstein Distinguished Educator Fellow. He now works as a Graduate Assistant at Florida International University contributing to STEM education research. For column queries: