Climate change and fireflies?

Question: I have only lived in New York City for a few years, but this is the first time I have personally noticed fireflies in the city. I wondered if this could be linked to climate change and if these magical bugs are coming out in greater numbers because of warmer weather?

Mike Hoffmann

Mike Hoffmann

Michael Hoffmann, entomologist and director of the Cornell University Agricultural Experiment Station has an answer:

What an interesting question! There is relatively little evidence in the scientific literature about the linkages between fireflies and climate change, except for documentation that firefly activity (including female emergence and “bright display”) occur earlier in the spring because of warmer temperatures associated with our changing climate (see Environmental Entomology 38(5), 2009) – firefly abundance, which is in decline worldwide, is likely due to the loss of firefly habitat and excessive artificially lighting at night.

One possible reason for the seeming increase in numbers of fireflies you are seeing in New York City may be affected by wet springs, a trend that will occur with climate change in the Northeastern U.S. We have just experienced a relatively wet spring and early summer. Firefly larvae (glow worms) feed on snails, slugs and other small invertebrates. With more moisture, the number of snails and slugs likely increase, providing more food for fireflies and insuring good populations of adults. Because some firefly larvae live more than one year, the moisture conditions of the previous spring and summer may also play a role. In addition, warmer winters may result in possibly reducing the mortality of overwintering larvae. This will be an interesting topic for continued future research!

Climate change will have a major impact on insect populations including changes in abundance as well as seasonality. Consider the devastation to the forests in Colorado because of an explosion in bark beetle populations. The extended drought, which is stressing the trees, combined with warmer winters and summers that benefit the bark beetle populations, has resulted in extensive tree death over an area of about 80,000 square miles. The fires in the Southwest we are now witnessing are due in large part to this combination of events driven by warmer and drier conditions.

Category: Climate Change Q&A

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