June Fireflies

Click for a larger view of a firefly, Courtesy Wikimedia, Bruce Marlin, Photographer, licensed under Creative Commons Attribution-Share Alike 2.5 Generic license
Courtesy Wikimedia,
Bruce Marlin, Photographer
Licensed under
Creative Commons Attribution-
Share Alike 2.5 Generic license

Most people are fascinated by unusual displays of light. Meteor showers, solar eclipses, and the stunning Aurora Borealis, or Northern Lights, are grandiose in scale and mesmerize onlookers. But people are also enchanted with the small life-forms that create their own light.

Bioluminescence, the production of light by living creatures, is an incredible phenomenon produced by certain mushrooms, scorpions, millipedes, bacteria, snails, worms, beetles, and nearly half of marine life including single-celled plankton, jellyfish, octopi, and fish. Some are also fluorescent by absorbing light rays and then emitting them as a different color.

But today we will focus on fireflies, also known as lightning bugs, which are actually beetles.

How, and why, do these creatures produce their own light? Scientists are still learning how the process works, but basically it is a chemical reaction involving luciferin, a light-emitting compound, being catalyzed by an enzyme and reacting with oxygen to release cool, light photons.

The “why” part is primarily for locating mates. But other species could also use it to lure prey, as a method of escape, and to warn predators.

The nighttime hours of late Spring and early Summer months are prime time for firefly activity. They live around wetland areas where the soil is moist and will start flashing when the sky is dark. Females remain fairly stationary atop tall grass and watch for males who fly around flashing various light signals. When a female approves of a suitor’s signal, she will respond with her own glow pattern which allows the male to find her. After mating, the female will lay eggs in the moist soil or leaf litter where they won’t dry out. The eggs usually hatch in 3-4 weeks.

The larvae live in the soil hunting worms, snails or slugs. At this stage they may actually begin glowing. They live in the soil for one or two winters before pupating and undergoing metamorphosis into the adult stage. And the purpose of the adult stage is primarily breeding.

While we enjoy seeing these insect “shooting stars” it is critical to avoid trying to capture them since the Utah populations are small and fragile. (Photos are available online on many websites if one needs to see them closeup.) Walking on the soil can kill the eggs or larvae, and light from automobiles, street lights and flashlights can disrupt their ability to see the flashing of their prospective mates. While the “Firefly Citizen-Science Project” from the Natural History Museum of Utah indicates sightings at more than 50 locations, careless actions, as well as loss of critical habitat, are actually causing a decrease in populations across the country.

Let’s do our best to be good stewards of the earth and only “observe” the amazing firefly.

This is Ron Helstern with Wild About Utah.


Image: Courtesy Wikimedia, Bruce Marlin, Photographer, Licensed under Creative Commons Attribution-Share Alike 2.5 Generic license
Text: Ron Hellstern, Cache Valley Wildlife Association

Reported Sightings:

24 June 2017
Today while waiting for local city fire works we saw a lighting bug or two. We are in West Haven.

Report your sighting

Additional Reading

Holly Strand, Firefly Light, Wild About Utah, 20 June 2013, http://wildaboututah.org/firefly-light/

Clayton Gefre, Sparks Fly: Researchers track firefly populations across Utah, The Herald Journal, http://news.hjnews.com/allaccess/sparks-fly-researchers-track-firefly-populations-across-utah/article_270ac8b9-3d3f-5a01-9b5b-ac22e89a54bb.html

Natalie Crofts, New Website Tracks Utah Firefly Sightings, KSL, https://www.ksl.com/?sid=34439516

Utah Museum of Natural History, Firefly Citizen Science Project, https://nhmu.utah.edu/fireflies

Firefly light

Click for a larger view of a firefly, Courtesy Wikimedia, Bruce Marlin, Photographer, licensed under Creative Commons Attribution-Share Alike 2.5 Generic license
Courtesy Wikimedia,
Bruce Marlin, Photographer
Licensed under
Creative Commons Attribution-
Share Alike 2.5 Generic license

Click for a larger view of Nibley Firefly viewing spot Courtesy and copyright Google EarthFirefly viewing spot
Heritage Park, Nibley, UT
2456 S 800 W

Access 800 W from either 2600 S
(from Hwys 165 or 89)
OR 2200 S (Hwy 89 only)
41° 41′ 23″ N 111° 51′ 17″ W

Courtesy Google Earth, Imagery Date 8/11/2011

Hi, I’m Holly Strand.

One of my greatest delights during childhood was to visit my grandmother in North Carolina. For around her farmhouse I could spend endless hours chasing and catching fireflies–we called them lightening bugs back then. As an adult, I am still captivated by the dancing lights that animate the muggy darkness, often with a background chorus of crickets and cicadas.

Flashing in fireflies evolved as a way to identify a mate. The male flashes his invitation while patrolling the local air space. If a female is impressed, she responds, either from the ground or at some perch in a shrub or on tall grass. Different species emit different flash patterns to avoid interspecific mix-ups.

Fireflies are very common in the moister, eastern half of the US. Look for them near ponds, streams, wet meadows and marshes. Many popular science sources will assert that fireflies don’t occur in the arid west. Or they will say that fireflies in the west don’t flash. For while the larvae of all firefly species glow, the adult forms of some species don’t flash. And those non-flashing forms are the species which are documented online and in collections for Utah and surrounding states.

Until recently I felt sorry that Utah kids don’t get to experience these magical bioluminescent displays. But on Monday night just before 10 PM, my family and I stood at the end of the sidewalk behind the soccer fields in Nibley’s Heritage Park. As the sky darkened, tiny amber lights began to wink on and off. An entire field of twinkling lights lay before us. I had to pinch myself to make sure I wasn’t dreaming.

I asked around and discovered that –in the last 10 years or so–there have been several sightings of flashing fireflies here in Utah. In 2002, biologist Jim Cane discovered some in River Heights. Utah State University’s Insect Collection features a 2007 specimen from Heber Valley. In recent years, additional sightings have been reported in Escalante, the Uinta, Spanish Fork and now Nibley.

We don’t know why Utahns are now able to enjoy these insect light displays. Have the flashing fireflies always been here and we just didn’t notice them? Did we notice them, but didn’t document it publicly? Or is the range of this particular species expanding? And if so, why?

To see the Nibley fireflies check our website www.wildaboututah.org. We’ve posted a map. And if you have seen flashing fireflies now or in the recent past here in Utah, let us know and we’ll post it on our website for others who might be nearby.

In general, firefly populations are declining around the world, and they are obviously still rare here. So if you run across them, treat them with respect!

Thanks to Utah State University entomologists Charles Hawkins, Ted Evans and Jim Cane for sharing their firefly expertise.

For Wild About Utah, I’m Holly Strand.


Image: Courtesy Wikimedia, Bruce Marlin, Photographer
Map/Satellite Image: Courtesy Google Earth
Text: Holly Strand

Reported Sightings:

22 June 2013
I just read the article about fireflies and want to say I’ve seen them in Mill Creek Canyon, just out of Moab (not Mill Canyon, which is north of town). I’m familiar with them from being in Missouri as a kid on vacation to see relatives.

Thanks for a great website! CM

24 June 2017
Today while waiting for local city fire works we saw a lighting bug or two. We are in West Haven.

Report your sighting

Sources & Additional Reading

Buschman, L L. Biology of the firefly Pyractomena lucifera (Coleoptera: Lampyridae). Florida Entomologist 67.4 (1984): 529-542.

Lloyd, James E., 1964. Notes on Flash Communication in the Firefly Pyractomena dispersa (Coleoptera: Lampyridae) Annals of the Entomological Society of America, Volume 57, Number 2, March 1964 , pp. 260-261. (James Lloyd is a leading authority on fireflies. He retired from academic duty at the University of FL, but here is a web page with some of his wisdom and musings. http://entnemdept.ufl.edu/lloyd/firefly/

(Boston) Museum of Science Firefly Watch
Volunteers help citizen scientists track firefly occurrences.

National Geographic. Firefly (Lightning Bug) Lampyridae

Phys.org news service. Jun 26, 2012. Romancing the firefly: New insights into what goes on when the lights go off. http://phys.org/news/2012-06-romancing-firefly-insights.html#inlRlv

Stanger-Hall, Kathrin F., James E. Lloyd, David M. Hillis. 2007. Phylogeny of North American fireflies (Coleoptera: Lampyridae): Implications for the evolution of light signals. In Molecular Phylogenetics and Evolution 45 (2007) 33-49.

Utah State University Insect Collection has over 117 cabinets housing approximately two million pinned insects and 35,000 microscope slides. Location: Room 240, Biology and Natural Resources Bldg.; Telephone: 435-797-0358