What makes a firefly glow?
Why do glowworms glow?
One of the most baffling mysteries of the insect world
has been what makes a firefly glow in the dark.
Fireflies, also called lightning bugs, are
luminous nocturnal beetles made up of about 1900 species living in
tropical and temperate areas. The common glowworm is a member of
the same beetle family (Lampyridae).
Fireflies range in size from a few millimetres up to about an
inch (25 millimetres), and have special light organs under their
abdomen. Females that lack wings are commonly referred to as
There are a few peculiarities about fireflies, one of which is
that some adult fireflies do not eat. Another is that frogs that
eat large numbers of fireflies start to glow themselves.
Another mystery came to light in July 2008 when a researcher
from the University of Queensland, David Merritt, found that
Tasmanian cave glow-worms deep inside dark caves are able to tell
whether it is day or night outside. Despite their continuously dark
environment, they light up brightly during the day and switch off
But the biggest mystery has been what causes them to glow.
Secret revealed at last
Neurobiologist Dr. Barry A. Trimmer was the lead author of a
paper in the journal Science in which he finally revealed
the secret of what makes a firefly glow.
The secret is nitric oxide. This is a dissolved gas that lets
the firefly's nervous system switch on its flash of light. Most
firelies produce short, rhythmic flashes.
In a complex arrangement between nerve cells, light-producing
cells, and an enzyme-assisted reaction, the lightning bug's lantern emits
that greenish glow so common in the early summer twilight in some
parts of the world.
We must add of course, that even though scientists now know what
makes the firefly glow, the whole complex arrangement shouts that
only the Master Creator could create and put together such an
amazing little insect in the first place.
Glowworm photo by Wofl is licensed under Creative Commons Attribution ShareAlike 2.0 Germany