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When Will The Fireflies Light Up Your Back Yard?

Wondering when you'll see fireflies (or "lightning bugs") glow on these warm summer nights? Watch for this backyard clue!

Watching fireflies (or “lightning bugs”) is a pastime we all look forward to on summer nights. But when can you expect to see their subtle glow light up your backyard? Weather could give you a clue.

Yes, fireflies, which are actually a type of beetle, share a relationship with weather that goes deeper than the summer solstice. Their larvae live underground during winter, mature during spring, and then emerge in early summer anywhere from the third week in May to the third week in June. What dates you’ll begin to see fireflies in your back yard is somewhat of a mystery, and changes from year to year. But scientists do know that air temperature and rainfall have something to do with it.

Muggy Bugs

Unlike people, fireflies love warm, humid weather. It helps them to survive. So in years when summer-like weather arrives before June does, fireflies tend to appear in lawns, gardens, and trees earlier than usual—sometimes as early as late spring. All the warmth from early summers and mild winters fools lightning bugs into thinking it’s later in the season than it really is, and so they emerge sooner. Mild winters also mean a larger lightning bug population in your back yard, since the young will have had an easier time surviving the cold.

Wet springs also lead to earlier firefly flash displays—likely because firefly larvae feed on snails, slugs, and pill bugs which are brought out by rains. The damper the soil, the more plentiful these creepy-crawlers will be, and the more food young fireflies will have to carry them into adulthood. And it’s the adult fireflies that flicker (mostly as a way to attract mates)!

As much as damp weather provides an ideal environment for fireflies, dry conditions provide the worst. Droughts and heatwaves stress firefly eggs and larvae, causing them to die off before they’ve had a chance to emerge. The dates when lightning bugs appear will also be delayed due to the heat stress.

Expect the Brightest Fireflies on the Warmest Nights

Weather not only plays a role in how soon you’ll see lightning bug flashes but how many flashes too. On warm and humid evenings, lightning bugs can light up a field as if it were a Christmas tree! But on cooler nights when air temperatures take a dip into the 50s, don’t be surprised if you wait a minute or longer to see a single flash. Why is this? Fireflies, like most insects, are cold-blooded (meaning they depend on heat from their surrounding environment to help them function), so their activity peaks when temperatures rise and slows when temperatures drop.

Or maybe you are planning to trek to the Great Smoky Mountains to view this year’s synchronous firefly display (it’s the largest population of synchronous fireflies in the Western Hemisphere, and begins May 30th ) Take a look at the video of this incredible event:

Have you seen fireflies yet in your backyard? Leave us a comment and “enlighten” us!

Check out these interesting facts about fireflies!

Farmers' Almanac - Hair coloring
Tiffany Means

Tiffany Means is a freelance writer and a degreed meteorologist. She specializes in weather forecasting and enjoys making the subject of weather (and the science behind it) more relatable. She currently resides in the Blue Ridge Mountains of North Carolina.

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dale york

tonight i saw glowworms in my backyard here in N.H. i’ve never before seen them, and i’ve lived here more than 50 years. not sure if they’re related to fireflies. must research.

Susan Higgins

Dale, we have a story on glowworms that might help. Take a look here.

Barbara

I live in Cleveland, Mississippi, and Over the past year have thought I saw a single firefly a couple of times, but wasn’t completely sure – because it was just one single flash out of the corner of my eye. Amazingly, the other night, we saw about 10 fireflies – July 22, 2021. I haven’t seen any since.
Does any one know why this would be? I am not sure what their range is. Is it possible a new population is trying to establish in our area?
We are in an area with a large number of acres designated to agriculture: Soybeans, Corn, Rice, and maybe Cotton. According to people that have lived and grown up here, there used to be fireflies, but significant amounts of pesticides likely wiped out the majority of firefly populations. I have heard of firefly sightings about 6 miles away, so have been hoping they would find their way to us.
Any thoughts?

Ivory

How close is your nearest farming community? We had them here as well in illinois, but this year there was a smaller amount and they have already died off. Normally this wouldn’t happen till later…some time in mid Aug maybe. The culprit is most likely a combination of insecticide and herbicide being sprayed by farmers. They cropdust here. It has affected our quail, butterfly, bee, wooly worm, toad/frog, firefly populations and others.

Barbara

We are surrounded by farming: used to be mostly cotton, but now primarily soybeans, corn, and rice. They don’t use insecticides on these crops like they do on cotton, and I’m sure you’re right – the spraying has definitely been detrimental to many things…
I was so excited to see them! But haven’t seen them again since. I am hopeful that they will make a comeback!

Matt Morley

Great article! Just saw my first of the summer in DC/Maryland.

Last edited 4 months ago by Matt Morley
Jennifer

I live and grew up in Southeast Michigan, and the only “lightning bugs” I remember seeing and catching growing up don’t appear until later in summer, come out at dusk, and flash a yellowish light for an hour or two. They slowly meander over lawns so they are easy to catch, and when they light up they glow for a 2-3 seconds. The past few years I have noticed a different kind of firefly that seems to stay around the tall grass in the field behind my house. These fireflies appear to fly faster than the ones I have always been familiar with, have quicker flashes of a whiter light, and fly around and flash for hours into the late night. I didn’t even realize there was more than one type of firefly because I don’t remember ever seeing any other than the slow flying, yellowish, long-flash fireflies.

Tory

North Western New York near Lake Ontario. The fireflies have been fabulous this year. Started about 10 days ago. Wish it lasted longer.

Susan Higgins

Yes, all that hot, muggy weather. Apparently, they love it!

Kreigh Tomaszewski

I live in Grand Rapids, Michigan, and the firefly’s have finally appeared the past few days, after our dry spring ended this past week with several inches of rain, and temps in the 80’s.

Katherine Underwood

We’ve had them for several weeks here in Northwest Georgia.

Frank Guy

Just noticed the fireflies in West Knoxville two nights ago. There’s been a few more every night.

Amy Holberg

Just saw them this week in North Carolina!

Ginny A Gardner

It seems like the fireflie population is way down.. Has anyone else noticed

Susan Higgins

Hi, Ginny, yes, we wrote an article that you might find interesting. Take a look at it here.

Lisa lodes

I live in Jersey and have been anxiously waiting for the light show. It’s the 3rd week in June and we usually have by now. I hope we get. I sure would miss watching them.

carolyn walters

I Live in Loganville Georgia we are south east of atlanta I am an a gardening nut and have been very sad over the years as we have little to no fire flys. One of the fondest memories I have of my childhood. but this year I have seen them seen some since late april 2021. Tonight is a firefly miracle I can just look out my front window and see them everywhere the little darlings are putting quite a light show. 6/18/21

Alice

In Pittsburgh, I haven’t seen any fireflies yet. I keep looking every night. They are usually out by early June. Nobody in this area has seen many, most say they have seen very few or none.

nel

Checking in and Central Illinois and I’ve seen exactly three fireflies but I’m so excited because my grandson is three he’s live in California is whole life he’s never seen a firefly so we are patiently waiting well maybe not so patiently LOL

Lori

My backyard and woods were full of fireflies 2am in Chester NJ

Karen Maskell

Spotted a firefly in the backyard (Minneapolis) today! It’s been years. Made my heart happy!

Last edited 5 months ago by Karen Maskell
Jenn

Jenn in Asheville NC. We’ve seen exactly 2. Most weeks still in the 70s and cooler still. Strange year. I’m beginning to worry about our little guys.

Aaron

Great article! Reporting from southwest Michigan, no fireflies yet, but we are supposed to be unseasonably warm this week (upper 80’s) so I’m hopeful! My twin girls think it’s the most magical time of the year, to go out and see the fireflies. They say it makes our yard and garden look like Pixie Hollow from the Disney movies about fairies (Tinkerbell, etc). 🙂

Pete

Yep, I’m in Southeast MI. Can’t wait! Even in my 50s, seeing them is always humbling and awesome.

Barry J Chapman

southeast michigan here, my trees are lit up tonight!

Char

Wow such great info, thanks for sharing.
Sadly I have not seen any in NC yet.

Julie Miller

In central NC, I have seen fire flies the last 2 evenings. My puppy loves trying to catch them in field. Lol

Ashton

I’ve just moved to middle Tennessee from east Texas and standing on my porch for a few minutes, I saw the most fireflies I’ve ever seen in my entire life. We might see a few every now and then but this was hundreds if not a thousand across the pasture. Today is May 15, 2021

Char

I lived in Elizabethton, TN in 2001 and I too saw more fireflies there than anywhere I’ve ever lived!

Jenn

I’m thinking all the NC fireflies might have moved to TN

Von

Yes I have seen firefly since yesterday morning at 3:30 started here on May 4th
Tennessee

Casey Nunez

Our Mississippi homestead has the synchronous fireflies so we created a viewing area for the public

JPop

Here in Southeastern, PA, the fireflies have emerged since Tuesday night on April 27, 2021. Tonight, Wednesday, April 28, 2021 more have emerged because of the unseasonably warm weather. Although, the humidity is quite low and from what I’ve read, fireflies prefer the hot, humid nights. These beauties usually arrive in mid-June around here. We’ve also had Swallowtail butterflies arrive way too early. Hmmmm!

Susan Higgins

Wow, that’s early for PA! Thanks for sharing!

Christine Steele

Lots of fireflies out tonight. April 13, eastern Ky

edwina.j.henry@gmail.com

Here in west TN as well! Was not even a warm night.

Tammy

I’ve enjoyed watching fireflies in the upper boughs of my backyard trees the last three nights. Yellow flashes. I’m in Richmond Virginia near the James River.b be

Betsy Loeb

I saw them in Richmond too last night,, April 18! I was shocked to see them so early!

Susan Higgins

It seems very early this year, doesn’t it! Thanks for commenting.

Jennifer stevens

I just saw about half a dozen huge fireflies behind my house, seems so early and I honestly have not seen them so big!

Jennifer stevens

Oh ya I live in steelville, mo

Susan Higgins

Interesting, Jennifer! It is early!

RebeccaJones

I have seen one firefly for two nights in a row. It’s only April 10th.

Jenny Lugo

April 9, 2021 6:00 am spending quiet time with the Lord and the empty lot next to my house here in East Texas had quite a few lightning bugs twinkling for my enjoyment.

Von

I was out at 3:30 yesterday morning during all the storms and I saw 2 fireflies while I was sitting quiet time with the father

Heather

Tonight (April 7, 2021) and last night I saw a single lightning bug flying about 15-20 feet up, which seems extraordinarily early. Usually I see them come out in June. I’m in the north Atlanta suburbs. We’ve had a couple of usually warm days (about 80 degrees) so maybe that’s why.

Last edited 7 months ago by Heather
Karen Hefner

This morning (April 10) we spotted Fireflies very high up in the trees before dawn. We were discussing how early it was to see them-and how high up they were. We are in the rural foothills west of Atlanta-close to the state line.

RebeccaJones

My lone firefly was high in the trees, also. Strange.

Lacy W

I have read before that there is a species of firefly that usually displays closer to dawn and higher off the ground. Perhaps it was that?

Sam

As I write this, it is Sunday October fourth. I live in western NY, it is currently 50 degrees and I have firefly larvae all over my yard. I have never experienced anything like this before. Usually fireflies are gone by September but my lawn is littered with firefly larvae. I caught one and did some research because I had no idea they were out this late in the year. Truly amazing.

Candice Williamson

Sorry, I failed to mention I’m in Upstate SC

Candice Williamson

Never have I ever seen fireflies in September. In fact, here, they are pretty much gone in late July. But I was just out front and was shocked to see firefly flashing and then I went out back and saw them there too. Not lots of them, only a few, but fireflies none the less.

Lori Kontz

Here in Latrobe, PA, I have yet to see even one firefly this summer! Maybe it’s because of the weather we’ve had this season? It’s been hotter than usual for much of the summer & we’re currently experiencing drought conditions. Fireflies like warm but humid conditions. I, for one, miss them.

JDM

Lots of fireflies in my Maine garden this year… the most I have ever seen.

Susan Higgins

We’re starting to see more of them here at the FAHQ! It’s nice to have them back. I think all this humidity has been helpful.

Jess

Central Texas, my backyard and my neighbors have dozens every year, I think because we are a “poorer” neighborhood, aka, nobody has that perfect grass that you have to spray poisons on, it’s more like just meadows or horseherb! 🙂

Diane Ballum

I live in So. N H. Had a great show in our back yard about 6 or 7 years ago, it was magical, but none since then. I miss them. 🙁

Casey

Last night was in the 70s with lots of fire flies and tonight it’s in the 80s and very muggy and not one is out

April

I am yet to see any this year. 🙁

Gnatty Bees

NYC 2020. It’s July, humid and in the 90s. Lots of fireflies in Central Park!

Susan Higgins

This is good news!

Arlene Milczarski

In Western New York we’ve had 9 days of 90 degree weather. I woke up a few minutes ago and there’s one flashing in my bedroom!

Christine Cervantes

I have never seen even one firefly. 🙁 I live in southeast Georgia, near lots of ponds and wooded areas and it gets hot and muggy here. I REALLY want to see them!

Veronica

I live in RI and I have only seen MAYBE 4 after 9pm? Sooo disappointed . I was hoping to show my grandbabies.

Rhi

I’m in Madison, Wisconsin and outlying cities and I have seen a total of 3 this summer. I almost hit the first one with my car, which is what reminded me that they exist and I started wondering where they’ve been. Then I saw one up in the sky, and tonight I found one stuck in my room.

Andrus Donna

Tonight, finally! The fireflies are putting on their show. A delight. And so reassuring to see Mother Nature is able to celebrate 2020 with no restraints.

Carla horne

Tonight in Pittsburgh the fireflies are lighting up like crazy,and there is a large amount of them

Cyrus

Very few fireflies this year so far south of Pittsburgh

Me

So many right now, a warm, muggy night in Central NY. Flashes seem so much bigger and brighter.

Katey

I’ve noticed this too!

Karen Royer

Say no to lawn chemicals (herbicides and pesticides) to give the lightning bugs a chance for successful life cycles.

Betty Yarbrough

Looks awesome! Is it too late to go see them this year. Where are dates and directions listed?

Susan Higgins

Hi Betty, we included a link in the story that takes you to their page and sadly, it looks like events are canceled for 2020.

Nancy

We had the 17 year cicadas this month by the millions, it seems, but have had many fewer fireflies than last year, here in Blacksburg, VA. I wonder if the cool weather, as well as about a week solid of rain just as they were starting to shine, slowed things down. Since others in the Virginia area are also seeing less this year, hopefully they are just late.

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