Ask The Entomologist: Fireflies

Firefly

Fireflies on a warm summer night is a childhood memory shared by so many of us. You may remember breathlessly running around the yard trying to catch them, the fascination of observing their abdomens glow from inside a jar, watching the swarm fly away when you release them at the end of the night. 

We asked our entomologist, Dr. Stoops, some questions about fireflies. 

What makes a firefly glow?

Fireflies are beetles in the family Lampyridae. They exhibit bioluminescence which is the biological production of light. The light is produced by a chemical reaction that involves a chemical called luciferin. When luciferin is combined with the enzyme luciferase (and other chemicals such as oxygen and Adenosine Triphosphate), light is produced.   

Where do fireflies go during the day?

During the day, the adult beetles are found resting on the ground or low on grasses and other vegetation.  

Where do they live in the US? Are they anywhere else in the world?

In the United States, most species of fireflies live in the Eastern half of the country. But the family Lampyridae is found in South America, Europe and Asia.

What do fireflies eat? And what preys on them?

Larval fireflies are predators feeding on other invertebrates such as insects, worms, and slugs. Some adult beetles are predators, some feed on pollen, and in some species adults don’t feed at all.

There is one species of firefly where the female beetles hide in the grass and mimic the light signals of the males of other species to attract them. They trick these males into thinking they have located a mate but when they land the female kills and eats the male.

Due to some distasteful chemicals produced, there is thought to be few vertebrate predators of fireflies.

Does Mosquito Authority treatment affect the habitat of fireflies?

It is very unlikely our treatments impact adult and larval fireflies because our mosquito control protocol does not treat the areas where adult and larval beetles are found. Habitat destruction of marshes and swamps where many of the species live is a greater threat to firefly populations.  

Dr. Craig Stoops LCDR MSC USN (ret.) is a retired U.S. Navy Medical Entomologist who has conducted mosquito control and research in the United States and around the world. Craig wields a B.S. in Biology from Shippensburg University, and both an M.S. and a Ph.D. in Entomology from Clemson University. He is Board Certified by the Entomological Society of America in Medical and Veterinary Entomology.