Lightning Bugs — Vanishing Memories Of Youth
February 18, 2020 at 2:35 a.m.
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Unfortunately, there have been recent reports that one of the fond memories of my youth may be lost. Lightning bugs, more commonly called fireflies, are facing increasing threats from habitat loss, pesticides and pollution. Their demise would be a tragedy.
There are three reasons likely to blame.
The first may be loss of habitat. Mangroves, forests, wetlands, rice paddies and marshes are vanishing together with fireflies. All are important because they provide special conditions to complete the fireflies life cycle.
Second is light pollution from cities, billboards, street lights and houses. Bright lights interfere with and outshine the mating signals fireflies use to attract females. Bright light also disrupts the feeding patterns of the females that glow to attract and eat males.
The third is the persistent use of insecticides and pesticides. Additional threats include global warming and water pollution.
Fireflies have been eloquently described by Sara Lewis, in her book, “Silent Sparks,” as follows, “Their resplendent displays change ordinary landscapes into places ethereal and otherworldly. Fireflies can transform a mountainside into a living cascade of light, a suburban lawn into a shimmering portal to another universe, a serene mangrove-lined river into a hypnotically pulsating disco.”
Since their evolutionary origin some 297 million years ago, beetles have been highly successful; they represent 38% of known insect species.
Fireflies rank among the most charismatic beetles, with distinctive bioluminescent courtship displays that make them a potential flagship group for insect conservation. With more than 2,000 species worldwide, firefly beetles exhibit surprisingly diverse life history traits, including nonluminous adults with daytime activity periods, glowworm fireflies with flightless females, and lightning bugs that exchange species-specific flash signals. Fireflies also inhabit ecologically diverse habitats, including wetlands mentioned above. Their larvae, which can be aquatic, semiaquatic or terrestrial, spend months to years feeding on snails, earthworms and other soft-bodied prey.
In contrast, firefly adults are typically short lived and do not feed. Some varieties are habitat and dietary specialists, whereas others are ecological generalists. Fireflies are economically important in many countries, including South Korea and Mexico, where they represent a growing tourist attraction.
However, as is true for many invertebrates, fireflies have been largely neglected in global conservation.
Fireflies originally evolved the ability to light up as a way to ward off predators, but now they mostly use this ability to find mates. Not all species produce light, there are several that are day flying and apparently rely on the odors of their pheromones to find each other.
Fireflies are filled with a nasty tasting chemical called lucibufagens, and after a predator gets a mouthful, it quickly learns to associate the firefly’s glow with this bad taste. The flashing not only helps to attract a mate, but also warns predators to stay away.
One species of firefly that cannot make its own lucibufagens acquires it by eating others that can. To lure victims, these fireflies mimic the flashing pattern of other species. When the unsuspecting male approaches to find a mate, instead it becomes a tasty treat to the tricky firefly. Each firefly species has its own signaling system.
The males fly around at the right height, the right habitat and the right time of night to attract females. The females sitting on the ground or in vegetation watch for the males.
When a female sees one making her species’ signal and doing it well, she flashes back with a species appropriate flash of her own. Then, the two reciprocally signal as the male flies down to her. If all goes well they mate.
Fireflies glow is produced in photocyes or light cells located in the insect’s abdomen. The light is the result of the chemical reaction termed bioluminescence which occurs when two substances, luciferin and luciferase react with one another when exposed to oxygen. The firefly regulates the flow of oxygen into its abdomen to turn its taillight on or off. Of note is that this cold living light is almost 100 percent efficient, losing only a fraction of its energy to heat. By comparison a standard incandescent light bulb is less than 10% efficient and an LED ranges between 40 and 50%.
Final Thoughts
Insects like fireflies are predators that help to suppress pest populations or they are pollinators that help to produce the food we need. Their disappearance could create havoc with food cycles, especially for the birds and other animals that feed on them. A recent article in the journal Bioscience suggests a number of countermeasures for conservation. It is worth reading.
Max Sherman is a medical writer and pharmacist retired from the medical device industry. He has taught college courses on regulatory and compliance issues at Ivy Tech, Grace College and Butler University. Sherman has an unquenchable thirst for knowledge on all levels. Eclectic Science, the title of his column, touches on famed doctors and scientists, human senses, aging, various diseases, and little-known facts about many species, including their contributions to scientific research. He can be reached by email at [email protected].
Unfortunately, there have been recent reports that one of the fond memories of my youth may be lost. Lightning bugs, more commonly called fireflies, are facing increasing threats from habitat loss, pesticides and pollution. Their demise would be a tragedy.
There are three reasons likely to blame.
The first may be loss of habitat. Mangroves, forests, wetlands, rice paddies and marshes are vanishing together with fireflies. All are important because they provide special conditions to complete the fireflies life cycle.
Second is light pollution from cities, billboards, street lights and houses. Bright lights interfere with and outshine the mating signals fireflies use to attract females. Bright light also disrupts the feeding patterns of the females that glow to attract and eat males.
The third is the persistent use of insecticides and pesticides. Additional threats include global warming and water pollution.
Fireflies have been eloquently described by Sara Lewis, in her book, “Silent Sparks,” as follows, “Their resplendent displays change ordinary landscapes into places ethereal and otherworldly. Fireflies can transform a mountainside into a living cascade of light, a suburban lawn into a shimmering portal to another universe, a serene mangrove-lined river into a hypnotically pulsating disco.”
Since their evolutionary origin some 297 million years ago, beetles have been highly successful; they represent 38% of known insect species.
Fireflies rank among the most charismatic beetles, with distinctive bioluminescent courtship displays that make them a potential flagship group for insect conservation. With more than 2,000 species worldwide, firefly beetles exhibit surprisingly diverse life history traits, including nonluminous adults with daytime activity periods, glowworm fireflies with flightless females, and lightning bugs that exchange species-specific flash signals. Fireflies also inhabit ecologically diverse habitats, including wetlands mentioned above. Their larvae, which can be aquatic, semiaquatic or terrestrial, spend months to years feeding on snails, earthworms and other soft-bodied prey.
In contrast, firefly adults are typically short lived and do not feed. Some varieties are habitat and dietary specialists, whereas others are ecological generalists. Fireflies are economically important in many countries, including South Korea and Mexico, where they represent a growing tourist attraction.
However, as is true for many invertebrates, fireflies have been largely neglected in global conservation.
Fireflies originally evolved the ability to light up as a way to ward off predators, but now they mostly use this ability to find mates. Not all species produce light, there are several that are day flying and apparently rely on the odors of their pheromones to find each other.
Fireflies are filled with a nasty tasting chemical called lucibufagens, and after a predator gets a mouthful, it quickly learns to associate the firefly’s glow with this bad taste. The flashing not only helps to attract a mate, but also warns predators to stay away.
One species of firefly that cannot make its own lucibufagens acquires it by eating others that can. To lure victims, these fireflies mimic the flashing pattern of other species. When the unsuspecting male approaches to find a mate, instead it becomes a tasty treat to the tricky firefly. Each firefly species has its own signaling system.
The males fly around at the right height, the right habitat and the right time of night to attract females. The females sitting on the ground or in vegetation watch for the males.
When a female sees one making her species’ signal and doing it well, she flashes back with a species appropriate flash of her own. Then, the two reciprocally signal as the male flies down to her. If all goes well they mate.
Fireflies glow is produced in photocyes or light cells located in the insect’s abdomen. The light is the result of the chemical reaction termed bioluminescence which occurs when two substances, luciferin and luciferase react with one another when exposed to oxygen. The firefly regulates the flow of oxygen into its abdomen to turn its taillight on or off. Of note is that this cold living light is almost 100 percent efficient, losing only a fraction of its energy to heat. By comparison a standard incandescent light bulb is less than 10% efficient and an LED ranges between 40 and 50%.
Final Thoughts
Insects like fireflies are predators that help to suppress pest populations or they are pollinators that help to produce the food we need. Their disappearance could create havoc with food cycles, especially for the birds and other animals that feed on them. A recent article in the journal Bioscience suggests a number of countermeasures for conservation. It is worth reading.
Max Sherman is a medical writer and pharmacist retired from the medical device industry. He has taught college courses on regulatory and compliance issues at Ivy Tech, Grace College and Butler University. Sherman has an unquenchable thirst for knowledge on all levels. Eclectic Science, the title of his column, touches on famed doctors and scientists, human senses, aging, various diseases, and little-known facts about many species, including their contributions to scientific research. He can be reached by email at [email protected].
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