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Monday, June 12, 2017

Summer Nights and No Fireflies...What's Happening to Them?

Summer is a time for picnics and outdoor parties that often extend into the evening hours. Watching the children running around having a ball with glow sticks got me sadly contemplating on what was missing in this picture. Years ago there were no glow sticks to entertain children after dark. Kids were enchanted with the stars and the magical mystery of fireflies. Some people call them june bugs, others simply call them lightning bugs. What is happening to them?

Just as with the bees, the answer lies with habitat loss, and pesticide use, but there is another factor and it is called light pollution.

These insects aren't flies, they are actually beetles, and that glow comes from a chemical reaction. 
Both male and female fireflies use their flashing lights to communicate. Their language of light is used to attract mates, ward off predators and defend their territory. Too much light caused by streetlights, car lights and suburbia in general, interrupts the sync of firefly flash patterns. Difficulty for fireflies to signal each other results in fewer larvae being born with every passing season.

Open fields and forests, waterways and bogs, are all disappearing as development makes its slow crawl across what was once uninterrupted habitats. Most species of fireflies thrive as larvae in rotting wood and forest litter at the margins of ponds and streams. As they go through their life cycle, most stay around where they were born. The environment of choice is warm with areas of wet spots.

The female lays about 500 eggs in sheltered areas that contain damp soil. After about a month the tiny larva hatch and begin feeding as they get ready for the next stage when they become pupae. The larval period can last from one to three years. During this stage the fireflies look like small worms and crawl along the ground. They are carnivorous and eat worms, snails and slugs by injecting a digestive enzyme and then sucking out the liquid. When big enough, the larvae digs into the ground and goes through the pupae stage. It forms a hard exterior shell that is what we are familiar with when we see them. This stage of metamorphosis takes them to the adult firefly which emerges in early summer. Once adults, the fireflies only live another few weeks. They may or not even eat during this short span. The purpose is to find mates and reproduce. So if light pollution creates enough of a problem to interfere with this process, these adults won't have the time to mate and lay their eggs before their life span ends.

This little video shows the life cycle of the firefly:

There are ways we can make a difference for these little guys. Make your own difference where you live. Avoid the use of herbicides and pesticides. Don't feel every part of your landscape has to be under control. Let spots naturalize to provide the habitats needed for all the stages of life. Learn what invasive species are a problem in your area and remove them to encourage the natives to thrive. Unless you have good reason for outdoor lighting to shine throughout the night, turn it off.

Children don't miss what they've never seen. Fireflies bring a sense of magic to our world and it would be a real loss to lose them.