Fast facts:
North America has 170 firefly family species
Light pollution can disrupt firefly life cycles
LITTLE ROCK — A little chemistry, a little coding and a whole lot of mating are just part of the story behind summer’s tiny fireworks show: the lightning bug.
“Fireflies have adapted the ability to glow and flash light patterns from their abdomens primarily for one reason, to communicate with other fireflies,” said Austin Jones, entomology extension instructor for the University of Arkansas System Division of Agriculture and the Dale Bumpers College of Agricultural, Food and Life Science.
“The vast majority of this communication is in order to find a date,” Jones said. “Different species use different patterns to discern who is who, and males and females often flash different patterns.”
Too much light
Fireflies thrive in areas where there is damp or boggy soils, tall grasses and forbs, tree canopy cover and leaf litter. When those are eliminated, so are firefly friendly environments.
“One form of pollution impacts fireflies more than most arthropods — light,” Jones said. “Since these animals have adapted to communicate with light, artificial lights can effectively drown out the communication efforts of fireflies and disrupt mating, or meals for the femme fatales.”
Males do most of the communicating, and Jones said it is probably “because the flashes can also attract would be predators, and bottom line, males are just more expendable than females are.”
In their language
Lightning bug signals can vary from species to species or location to location, differentiated by color, length of flash, brightness, frequency and grouping of flashes or the shape the light makes as the insect flashes and flies. For example, Photinus pyralis males fly upwards while making a sustained flash, resulting in a J shape, according to the National Park Service.
“Bioluminescence is the light produced by living things via chemical reactions,” Jones said. “Many marine organisms are bioluminescent and fireflies are the most common example of terrestrial organisms that can bioluminesce.”
The light is created from a chemical reaction within a clear portion of the exoskeleton. These chemicals include the light-emitting compound luciferin, the enzyme luciferase; adenosine triphosphate, a molecule that helps living organism manage energy, and magnesium.
“The on/off switch for the reactions is thought to be exposure to oxygen via the insect respiratory system, which is an intricate network of air passageways that exist throughout insect bodies,” Jones said.
Other examples of bioluminescence, Jones added, include fungus gnats, click beetles that have glowing eyespots, and some centipedes and millipedes.
A family of beetles, Phengodidade, known as the glow worms, have larvae and larviform females, which don’t metamorphosize into winged beetles.
Stealing the light
Some species use the glow for nefarious purposes.
“One group of fireflies in the genus Photuris, known by some as femme fatale fireflies, have mastered the art of responding to the flashes of males of other firefly species,” Jones said. “Once an amorous male suitor arrives at what he believes to be a receptive mate, the femme fatale firefly will instead eat him.”
With that meal, the femme fatale takes on the unsavory chemicals that previously protected the insect for her own use.
How many types of lightning bugs are there?
Jones said lightning bugs, or fireflies, are part of a beetle family Lampyridae.
“It's a pretty fitting family name considering that most are known to light up like a lamp,” Jones said. “However, not all fireflies have the ability to make light and are known as the dark fireflies. These species are active during the daytime and communicate with each other using chemical cues as opposed to light signals.”
There are about 170 described species of lampyrids in North America, and more than 2,000 species globally.
“With fireflies being of little economic importance, they have been historically understudied and some say that there may be just as many species yet to be discovered and/or properly identified,” Jones said.
However, they can be beneficial in the garden, with some feeding on garden pests such as slugs and snails.
Wait. They’re not bugs?
The term “bug” can mean lots of different things to different people but there is a definition.
“To most, any small creature with an exoskeleton could be called a bug and would include things that are more appropriately called arthropods, which means ‘jointed foot,’” Jones said. This group has features like exoskeletons, segmented bodies and multiple jointed appendages.
However, “true bugs” belong to an order known as Hemiptera, which includes about 60,000 species of insects that use mouthparts that resemble a drinking straw to pierce and suck, Jones said.
“Things like cicadas, stink bugs, assassin bugs and bed bugs are true bugs, but other insects like ladybugs and June bugs are beetles that have chewing mouth parts and are technically not true bugs, even though bug is in their common name,” Jones said.
What’s their life cycle?
Jones said that fireflies, as with all beetles, have a complete metamorphosis that includes egg, larva, pupa and adult stages.
“There are many different life histories among the wide array of species, but generally the larvae can be considered predators that live on and in damp soils and decaying leaf matter,” he said.
“Lifecycles can range from a few months to several years with adults only living a few weeks and sometimes not even long enough to feed at all.”
