Why Do Some Insects Glow?

Why Don’t Cockroaches Glow?

The idea of glowing cockroaches sounds odd… also, would that make them more or less creepy? Yikes! Either way, it is not something we have to worry about as there have not yet been any cases of people infested with glowing cockroaches. But why don’t insects like cockroaches, ants, or bees glow while others, such as fireflies, do.

Bioluminescence is the emission of light from an organism which occurs when chemical energy is converted into light energy within a being’s system. In the case of insects that display this phenomenon, the system is able to function due to the reaction between a particular type of molecule (luciferin) and an enzyme (luciferase). The luciferase catalyzes the oxidation of the luciferin, thereby producing light. As a general rule, bioluminescence is more likely to be found in water than on land, which is why we don’t come across a lot of glowing bugs. However, for those that do, it can serve a multitude of various purposes from attracting mates and prey, to warding off predators or providing a form of camouflage.

Most Well-Known Bioluminescent Bugs

In the world of bioluminescent insects, there are a few “star” glowers that are worth a mention:

Fireflies/Lightning Bugs & Glow Worms

While grouped together, these insects are not the same, however they are more similar than most people originally consider them. They are actually two different species within a family of beetles known as the Lampyridae (of which there are over 2,000 different species).

The adult females of the Lampuris noctiluca greatly resemble their larval form, which accounts for their colloquial name: glow worms.

Their cousins, the Lampuris photinus as what we know as fireflies and their subspecies Phontinus pyralis, are the most commonly found fireflies in the United States and are the ones you are most likely to catch with your children on warm summer nights.

Railroad Worms

Known scientifically as Phengodid phrixothrix, these insects, as well are their larvae emit green and red light. Uniquely, they are the only insects that possess bioluminescent red light.

Yellow-Bordered Flower Buprestids

Strikingly physically similar to fireflies, the Acmaeodera flavomarginata are a unique type of beetles that practice mimicry for protection. This form of camouflage is used in an attempt to deter predators by appearing to be fireflies.

Glowing Roaches

There actually are glowing cockroaches! However, at the same time, there are not. A particular species of roach known as the Lucihormetica luckae appeared to emit a yellowish glow and was thought to possess bioluminescent abilities. However, upon further scientific investigation by a team of bioluminescence experts and entomological researchers, it was found that the roaches were not actually emitting any amount of measurable light… so what lead to this confusion?

Well, the roaches were glowing, but not by their own volition. In a very rare phenomenon, it was discovered that the roaches in question were being plagued by a pathological bacterium. The bacteria colonized on the backs of the roaches causing the glowing effect. So, it was the bacteria that was actually bioluminescent, not the cockroaches themselves.

Bioluminescent Insects

In short, while the scientific world has a good grasp on how and why some insect-based bioluminescence exists, others (such as blue light-emitting systems) are still a mystery and we have a lot to learn.

Citations

Bioluminescent Insects – Bugs That Get Confused With Fireflies (no date) Firefly. Firefly Research and Conservation. Available at: https://www.firefly.org/bioluminescent-insects.html (Accessed: November 24, 2020).

Bioluminescent Insects Glowing in the Darkness (2018) Scribol. Available at: https://scribol.com/environment/animals-environment/bioluminescent-insects-glowing-in-the-darkness/6/?as=799 (Accessed: November 24, 2020).

Daniels, S. (2019) Facts About Silkworms, Sciencing. Available at: https://sciencing.com/silkworms-5455701.html (Accessed: November 24, 2020).

The glimmering world of glow-worms (no date) Natural History Museum. The Trustees of the Natural History Museum. Available at: https://www.nhm.ac.uk/discover/the-glimmering-world-of-glow-worms.html (Accessed: November 24, 2020).

O’Neill, M. (2020) Unraveling the Mystery of Insect Bioluminescent Systems, SciTechDaily. Available at: https://scitechdaily.com/unraveling-the-mystery-of-insect-bioluminescent-systems/ (Accessed: November 24, 2020).