It was with mixed feelings that I read in the July issue that people were being encouraged to leave their porch lights on at night during National Moth Week to attract and document local moths. While I’m totally in favor of citizen science, documenting biodiversity, expanding our knowledge of local biota, etc., etc., there are some serious ethical issues involved in this case. One is the current dire state of insect populations. Many insect species, especially those such as moths that undergo complete metamorphosis, have only a few days (or nights) of adult life in which to breed and they cannot afford to spend them bashing themselves pointlessly against lights. Not only do huge numbers of insects waste precious time in this activity, they fall easy prey to bats and birds in the process, good news for the bats and birds but only as long as there are insects. In fact, insect declines in urban areas have been attributed in part to outdoor lighting. Another issue is the contribution of outdoor lighting to the larger problem of light pollution, which disrupts bird migration and diminishes human appreciation of the night sky. And then there’s the whole energy conservation matter.
I don’t really believe that the number of lights that might be left on for a week for National Moth Week is going to make much of a difference in the grand scheme of things, but millions of lights left on every night have a huge impact and the problem can be addressed only one light at a time. I would like readers to be aware of the consequences of outdoor lighting and refrain from leaving lights on at night without very good reason. If night lighting is absolutely necessary, steps can be taken to minimize its impact. A Web search for “reduce impact outdoor lighting” will produce numerous suggestions.