So you say you found a glowing worm in your grass? How about on the side of your house? If so, don’t worry, you’re not crazy. What you saw can be any number of insects in their larval stage. There are four different species of fungus gnat (small flies with a short life span) that are glowworms when in the larval stage of life. Before becoming flies, the larvae look a bit like worms and glow through a process called “bioluminescence.” Bioluminescence is the emission of light by a living organism.
Fungus gnats are not fireflies. In fact, they are considered a pest by many, although they do assist in the decomposition of organic matter and help spread the seeds of certain plants and mushrooms. These glowworms live primarily in New Zealand and Australia.
Glowworms often look like worms but they are not. All are insects in the early stages of development. Although the term glowworm is scientifically dedicated to the four fly species mentioned earlier, it is the common name used for various groups of insect larvae that glow. Many beetles also glow including the popular firefly that can be seen at night during warm weather.
Fireflies, also known as lightning bugs, are not flies at all. In fact, they are winged beetles for the lampyridae family of insects. Fireflies create light from biological chemicals they produce. This light can be yellow, green or red.
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There are 2,000 firefly species found throughout the world. They prefer warm and tropical environments which is why they can only be seen during warm weather months in some climates. The larvae of fireflies also glow, giving them the common name “glowworm.”
Other species commonly referred to as glowworms due to their natural tendency to glow at different stages of the lifecycle include:
Rhagophthalmidae, a family of beetles that live in Asia, have organs that glow. These beetles might be relatives of the firefly but it is not presently confirmed. Very little is actually known about these beetles. The females are wingless and look like larvae when at their final stage of development in the lifecycle.
Phengodidae, also known as glowworm beetles, live throughout the world. They are predators and feed on millipedes and other insects as well as soil and litter. The wormlike larvae also glow during development.