Effects of outdoor lighting on moths

Skyscraper (FMC Building, Philadelphia), with decorative blue lighting illuminating its façade. In the visible light spectrum, blue light attracts the greatest diversity of moth species. 

In 1988 I wrote a paper on how artificial lighting outdoors at night affects moths. I noted how artificial lighting has been blamed for declines in the abundance of giant silk moths. Populations of these big, beautiful insects had plummeted around urban areas. I reviewed how artificial lighting disrupts numerous life functions of moths. These include flight, navigation, vision, migration, dispersal, oviposition, mating, feeding, crypsis, circadian rhythms, and photoperiodism. In addition, I noted that attraction of moths to lamps exposes them predation by birds, bats, spiders, and other predators.

But I found that despite these severe adverse effects, evidence incriminating outdoor lighting for declines in moth populations overall was sparse. Outdoor lighting is merely one of many environmental insults, including habitat destruction, pesticides, and introduced parasites.

Since this assessment, research has shown more clearly how outdoor lighting compounds other environmental disruptions that undermine populations of moths. For example, in a study of street lighting, Emmanuelle Briolat and colleagues found that caterpillar abundance was lower in illuminated habitats compared to similar habitats that were not illuminated.

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View my published research on effects of outdoor lighting on moths.

Double banded grass veneer moth (Crambus agitatellus) attracted to an illuminated sheet in our garden.

Boxwood leaftier moth (Galasa nigrinodis) attracted to an illuminated sheet in our garden.