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Fireflies Make Surprise September Re-Emergence in Central Texas

Miguel Guitierrez Jr./KUT


When a lot of people suddenly notice the same thing at the same time, it might be worth looking into. That was the idea behind a story KUT reported earlier this year when a lot of people noticed an unusually large number of fireflies lighting up the evening.

Credit Mose Buchele
Elizabeth "Wizzie" Brown is an entomologist with Texas Agrilife Extension Services.

Most of the fireflies disappeared by August, as they normally do. But now, they're back. 

Wizzie Brown is an entomologist with Texas Agrilife Extension Service in Travis County. She says some of the same factors that brought the bugs out en masse this spring account for their surprise September second act.  

“If you think about when we had that peak of fireflies in the spring, and the environmental conditions that we had going on there, which was lots of rain, we had that episode again in August where we got lots of rain,” says Brown. “So those firefly populations are popping back up.”

The rains encouraged other insects, like mosquitos, to come out in large numbers as well.

Brown says just because the August rains encouraged a new generation of fireflies to emerge, it doesn’t mean there will be fewer of them next spring. That will largely depend on weather conditions over the winter and into next year.


But Central Texas' year-of-lightning-bugs could go against a national trend.

There’s no hard data on this, but a lot of researchers think lightning bug numbers are declining in most of the country.

“Everything about the ways we are developing the land suggests that it would be eliminating fireflies,” says Fitchburg State University's Dr. Chris Cratsley. He works on the citizen-science project FireFlyWatch, where you can report firefly sightings online. 

Cratsley is talking about big development, like digging up and paving the earth. But he says little things you do in your backyard can also have an impact. Cutting lawns too short can hurt the bugs. Using pesticides might, too.

Then there’s light pollution. Too much light can confuse the insects, causing them to emerge at the wrong time, or making it difficult for them to find each other in the night. 

“With the fireflies a lot of them will do their flash signals to either find mates to breed, or they’ll do it for finding food,” Wizzie Brown says. “There are some species that will mimic the flash patterns of other fireflies to draw them in, and then they’ll eat them. It’s awesome!”

If you want to help out these sparkling, and only occasionally cannibalistic, beauties, there are some things you can do. Cratsely suggests leaving parts of your lawn a little wild, turning off your outdoor lights and maybe thinking twice before applying pesticides. If people follow those tips, and if downpours continue, we might see more lightning bugs a year from now.

Mose Buchele focuses on energy and environmental reporting at KUT. Got a tip? Email him at Follow him on Twitter @mosebuchele.