Are Fireflies Disappearing?
I grew up in far western Nebraska in the 1980's. Climate-wise, my hometown sits on the edge of the high-dessert of the foothill of the Rocky Mountains. So we had hot, but dry summers. The kind of summer day where it would be 95 degrees at 3:00 PM and 55 degrees at 3:00 AM. So I never saw many fireflies, or lightning bugs, when I was a kid. Except when we'd visit family in eastern Nebraska, near Omaha.
I think my disgust with bugs began on one of those visits, when after being so excited to see fireflies, I captured a coffee can full of them, then promptly spilled the can on me. Covered in creepy, glowing crawlers, my excitement at experiencing fireflies quickly dried up.
When I went to college in central Nebraska in the 1990's, you knew you were deep into summer when evening was light up with the little, erratic tracers.
Living in Sioux Falls is the same experience, June and July mean fireflies in the backyard, my kids chasing them with their own coffee cans. But, does it seem like there are fewer fireflies each summer? Are the numbers of these gross goo-bags with wings decreasing? Are we looking at a world without another disguising bug?
Sara Lewis, professor of evolutionary ecology at Tufts University, and author of Silent Sparks: The Wondrous World of Fireflies says that yes, the numbers of fireflies are dropping. The suspect is a combination of loss of habit, light pollution and possibly pesticides.
Fireflies, or lightning bugs if you're from a place that calls all pop Coke, love a life of fields, forests, and marshes. When those places get turned into fields of duplex condos and strip-malls, they don't have enough space to do their firefly stuff.
Light pollution, in other words, all the lights we need to see in the dark in cities and towns, causes a disruption in the insect's love life. The reason that their butts glow is to attract a mate. All those streetlights end up acting as a kind of blocker for fireflies on the lookout for love. The less dark it is the harder it becomes for their luminescent signals to be seen by potential partners.
Pesticides may be causing problems for baby fireflies. They are born and grow-up underground, or in water.
"Broad-spectrum insecticides like malathion and diazinon can accumulate in soils and waterways, and at high levels, these indiscriminately kill insects, including beneficial ones," Lewis said. The insecticides can also kill off food for the young fireflies. They eat worms, they must think nobody likes them.
There are over 120 species of fireflies in the United States. If you want to lend a hand to help the colorful pieces of bat food, Lewis has some ideas.
- Minimize light pollution by only using outdoor lighting where necessary,.
- Avoid using broad-spectrum insecticides, and only use them when problems arise.
- Have small piles of branches and leaves (a "good environment" for larval fireflies).
- Let the grass in part of your yard grow taller. This lets the soil trap moisture. Fireflies lay eggs in moist places.
It does look like there are fewer fireflies each summer than in years past. But, they aren't all gone, and it looks like there is something people can do.