Fireflies, or lightning bugs as my dad used to call them, are a welcome sight due to their spectacular nighttime displays. We usually see them from the middle of June into July in our backyard.
Fireflies, however, are actually not flies at all; they are beetles. There are over 165 species of this awesome insect found in North America, with most of them found east of the Mississippi — probably because they like moist soils and decaying organic matter where slugs and worms and other larvae live.
Why Moist Soils and Decaying Organic Matter?
Fireflies are of the family Lampyridae. Like all beetles, they undergo complete metamorphosis with four distinct stages: egg, larva, pupa, and adult. Adult female fireflies lay their eggs in moist soil. After they emerge a few weeks later, the larvae live in the moist soil or beneath decaying organic litter, eating slugs, worms, and other soft-bodied insect larvae. After a couple of months, to a year or more, during the late spring, the larvae will pupate underground and emerge as adults ready to mate.
We are fortunate that our backyard is compromised by only a little stray urban light. So as dusk settles in, the fireflies flicker over our prairie and lawn. They are signaling their desire to mate.
Most adult firefly species are pollinators. With diets consisting primarily of pollen and nectar, fireflies play an important role in the propagation of many flowering plants. They have mouths that are well designed to eat other bugs. Some scientists think adult fireflies feed on the nectar of plants and flowers, while the females of this genus may eat males, sometimes in the middle of mating.
Like pollinators in general, firefly populations are in decline. When we first planted our prairie, we saw hundreds in the evenings; now we’re lucky if we see five to eight in an evening. Blame it on climate change and many other factors. “Average temperature and rain fall amounts, pesticide usage, artificial lighting along streets and the outside of homes, amount of organic litter and loss of habitat including the expanses of lawn where female firefly cannot lay eggs, all influence firefly survival. There is also some evidence that firefly populations do not move away from where they started life, so local populations once lost completely do not recover on their own.” (Pollinators – Welcome)
Knowing that fireflies like moist soil and decaying organic matter gives us a hint about what we can do to help attract fireflies to our yards. Leave part of a downed tree or two, and the natural litter that comes from living ones. Mow your lawn at three inches or more; fireflies like to mate in long grass. Provide a water source like a small pond or stream. Avoid using pesticides. And most importantly, reduce light pollution as much as possible.
We love to see fireflies on a warm, humid night. They raise our spirits and bring smiles to our faces; they help us remember the good old days when we were young and full of energy. I hope they never fade away!
This is Pollinator Week 2021 (June 21-27). More information about fireflies.
Transmittal photo courtesy of Beneficial Bugs.