Fireflies, lightning Bugs, Lightning Beetles

Order: Coleoptera (beetles)

Family: Coccinellidae

How to identify:

As with most insects, fireflies have six legs and four wings. Their size ranges between ½ to 1 inch (Fireflies, National Wildlife Preservation) and usually are black with either orange,yellow, or red coloration on their backs. These insects have long, flat bodies and unlike most beetles, their wings are soft and bendable. They are most commonly known for their bioluminescent abdomen, or ability to glow, which is used to find a mate.

Advanced ID: Lampyridae have a long, slender, and soft body. Their elytra are held flat over their abdomen, covering it entirely. The thorax is oval-shaped, with the pronotum covering their heads from above. Their head has large compound eyes and hypognathous mouthparts.

Ecology

Metamorphosis Type: Complete metamorphosis. All larvae are bioluminescent and called glowworms (Lohmiller, 2021). 

Geographic Range: Fireflies are found in temperate regions on every continent except Antarctica (Fallon et al., 2019). 

Habitat: Includes meadows, marshes, damp woodlands, and gardens. They mostly are seen in the evening during early summer, when the weather is humid and warm (Fallon et al., 2019). 

Trophic Level: Omnivores

Food: Glowworms (firefly larvae) are predators and eat other insect larvae, snails, and slugs. Adults can be predatory (eating other insects, including other fireflies), herbivores (eating plant nectar and pollen), or not eat anything at all (with a very short adult stage). They have grooved mandibles that help them catch, hold, and tear apart their food (August et al., 2021). 

Why should we care?

Human Uses: Fireflies produce the enzyme luciferase, which is a substance that helps fireflies stimulate the glowing through a chemical reaction. We have now synthesized this enzyme and use it in forensics and medicine, mostly for its detection of magnesium and ATP. NASA used luciferase as one method to find signs of life in soils from other planets and asteroids (Fireflies’ Light Gains New Uses in Medical and Technical Research, 1975)! A more recent find involves cancer imaging; The successful gene expression that shows luciferase in cancer cells allows for more accurate imaging of the growing and spread of the cancer cells (Lyons, 2003). 

Conservation Status: Most species are experiencing an overall decline in population, with some classified as endangered. This is primarily due to habitat loss, climate change, and the use of fertilizers and pesticides (IUCN, 2021). And because fireflies rely on their flashing light patterns as a significant part of their courtship rituals, light pollution (e.g. light from automobiles, buildings, parking lots, etc.) plays an important role in decreasing mating opportunities, causing further population decline. To address some of these issues, efforts are underway to restore firefly habitats and reduce light pollution during mating season in known firefly habitats (Firefly Conservation and Research, n.d.). 

Because fireflies are a well-known species, they are considered a “flagship species,” used as a symbol for the conservation of biodiversity or a habitat. Additionally, they are “indicator species,” used to assess the health of a habitat. This provides yet another reason to encourage the public to conserve fireflies and make efforts to protect them (Fallon et al., 2019; Hagen et al., 2015).

Did you know?

• Fireflies, or lightning bugs, are actually beetles, so entomologists (scientists who study insects) tend to call them lightning beetles.
• In the Great Smoky Mountains of Tennessee, a special event takes place, illuminating the summer nights. Each species of Lampyridae has a unique pattern of flashes, enabling them to find mates within their species. This is similar to how different species of birds sing different notes and pitches. The males of the synchronous firefly (Photinus carolinus) have taken this to a new level by flashing in unison! For hours, entire valleys full of this species flash on and off simultaneously, prompting people to drive long distances to witness this phenomenon (National Parks Service, 2021).

Researcher’s Biography

Larisa Paxton
Completed this research within Dr. Shelly Thomas’ Entomology course

Suggested Citation:

Paxton, Larisa. (2021). Fireflies, Lightning Bugs, Lightning Beetles. Rowan University Arboretum. https://arboretum.rowan.edu/learn/explore-insects/fireflies/