Fireflies

What do you call those flashing beetles that light up in the summertime?  Is it a firefly or a lightning bug?  Different areas of the U.S. call these beetles one or the other or, sometimes, use the terms interchangeably.  Fireflies and lightning bugs refer to beetles in family, Lampyridae. 

I recently visited my family in Ohio and got to return somewhat to my childhood, being giddy over the number of fireflies I discovered emerging with their gentle flashing patterns at dusk.  Yes, I ran around like an idiot catching them, but after photos were released. 

Larvae are nocturnal and feed on small animals, including snails.  Larvae prefer moist environments, with some being subterranean or semi-aquatic.  Some larvae can emit short glows which are used to warn predators that they are distasteful.

Adult beetles are around ½ an inch long, slender, and soft-bodied. They have a shield-like structure, the pronotum, which covers their head from above.  The last few abdominal segments may be modified to emit light, but not all Lampyridae are bioluminescent.

Some fireflies are bioluminescent which means they have a chemical reaction that occurs within their body causing them to light up. When fireflies combine oxygen with calcium, adenosine triphosphate (ATP) and the chemical luciferin in the presence of luciferase, a bioluminescent enzyme, light is produced. Light from a firefly does not give off heat which is important to ensure survival of the beetle.  Fireflies control light flashing by controlling the oxygen that reacts with other chemicals needed to produce light.  

Adults use flash patterns to identify those of the same species as well as determine location of the opposite sex.  Female fireflies choose their mates based upon flash pattern characters; males with higher flash rates and increased flash intensity are preferred.

Adults feed on nectar, pollen, other fireflies, or many do not feed.  One group of females in the genus Photuris lure in males from the genus Photinus by mimicking the flash pattern of female Photinus.  When the male comes in to mate, instead of mating he is eaten. 

It is thought that disappearing habitat along with light pollution are playing a part in the decline of fireflies.  How can you help fireflies?  Turn off lights at night to help reduce light pollution (you’ll get the added benefit of less insects being drawn to areas where they can possibly get into your house).  Create water features in your landscape to provide areas of moisture required for larvae.  Target pesticide usage and make wise pesticide choices to reduce the possibility of effecting non-target organisms.

For more information or help with identification, contact Wizzie Brown, Texas A&M AgriLife Extension Service Program Specialist at ebrown@ag.tamu.edu.

This work is supported in part by the Crop Protection and Pest Management, Extension Implementation Program [award no. 2021- 70006-35347/project accession no. 1027036] from the United States Department of Agriculture (USDA) National Institute of Food and Agriculture.

The information given herein is for educational purposes only.  Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by Texas AgriLife Extension Service or the Texas AgriLife Research is implied.

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