There is always that confusing question, “What do fireflies eat?”, that crosses the minds of people when they see that charming little spark in the dark.  There are some that believe that fireflies do not eat anything at all.

Fireflies live in the development stage for most of their lives.  If you can understand the eating habits of the larvae, you can better appreciate how they function in relation to the environment around them.

During the larvae stage they feed by either hunting prey or feeding off of decomposing bodies.  Others prefer to consume something living for dinner.  They will often attack earthworms, ants, snails, shellfish and many other arthropods.  They do this by injecting their prey with a digestive liquid that actually anesthetizes their victims.  When their prey becomes immobile they begin eating it with their strong jawbones.

When the firefly becomes an adult then the question, “What do fireflies eat?”, changes drastically.  Fireflies transition from a carnivore into an herbivore.  They no longer have a taste for flesh so now the illuminating fliers feed on dew droplets and flower pollen.

Humans Threaten The Firefly

Humans are the biggest threat to the firefly population.  The use of strong pesticides, river pollution (mainly from large companies) and the development of land has resulted in the sad depletion of fireflies.  The largest reason why you do not see as many fireflies anymore is because of light.  As towns and cities continue to grow, the lights from buildings, cars and traffic stops are driving the firefly to move further away into the country or deep into the woods.

Additionally, as waterways become more developed, fireflies have less places to lay their eggs.  Farmers are now being encouraged to add fireflies to their recreational Eco-farms to help in preserving these creatures.

Biology of The Firefly

If you can observe a firefly when they are not acting as your guide in the dark, they are brown and occupy a very soft body.  Although they are a member of the beetle family, they have a much more leathery elytra.  Females and males look really similar and at first glance are very hard to tell apart except for the characteristic that females have compound eyes.  Most fireflies are nocturnal but there are some that are diurnal, however this species is non-luminescent.

After a female mates with a male, a few days later she will lay her eggs in the ground just below the surface.  Approximately four weeks later these eggs hatch and then this larva feeds all summer long in their carnivore state.  These are often called glowworms.

Over the winter they will burrow themselves underground or in tree bark and then they resurface in the spring.  After they eat for a couple of weeks they eventually become an adult.

What Sparks That Light?

Bio luminescence is the chemical reaction that causes fireflies to light up.  The light-emitting organs are generally found on the lower abdomen of the firefly.  Although all fireflies glow when they are in the larvae stage, it is for a different reason.  As larvae they light up to warn predators to stay away and as an adult the bio luminescence is used as a sexual selection.  The light is a way of communication and a steady or blinking glow means different things.

Tropical fireflies are a special treat to observe because they synchronize their pattern of flashes among an entire group. The phenomenon is called phase synchronization and in the Malaysian jungles along the river bank their light is synchronized precisely.  For fireflies that don't produce light, they signal mates with pheromones.

Fireflies are complex little creatures that go through several stages in their lives from eggs to carnivore to herbivore.  They are highly intelligent and should be appreciated as much as possible before environmental issues drive them away for good.