2024 Firefly Recap

The 2024 firefly season is over, and the results of season 7 show a continuing downward trend. I started monitoring fireflies at my parents' house during the summer of 2018, counting the number of flashes seen in 3 separate 10 second periods. I spaced my observation periods in 10 minute intervals, each with deepening darkness. Season 3, in 2020, was the highest total count with 708 flashes counted. Every season since then has seen totals lower than the previous.

Generally, firefly populations, like other insects, are decreasing. Reasons for this include habitat loss and degradation, pesticide use, and increased light pollution. Of course, local conditions will drive population trends in different areas. What caused my population to decrease is unknown, although cooler than usual spring temperatures could contribute.

From 2022 to 2023, there was a 25% decrease in number of flashes. Naturally, I was very curious as to whether or not the population would rebound in 2024, or even remain steady. Sadly, the numbers got worse. In 2024 the count was only 276, a decrease of another 26% on top of the 2023 decrease. That's a decrease of over 60% of the peak in 2020.

The charts below show firefly activity annually by daily flashes and annually by total flashes per year. You can see peak activity in late June and early July until 2023. 2023 peaked late and 2024 peak. Both years peaked at a rate lower than previous years.

Annual firefly count by day

Annual firefly count by yearly total

Once again, I'm curious to see if the population will rebound or continue to dwindle. However, for personal reasons I'm considering ending my firefly observations, at least at the current location. If I do chose to continue, it will be interesting to see what happens.

Firefly Watch 2022

The 2022 season of Firefly Watch was the most disappointing so far. There was a dramatic decrease in the number of flashes counted from 2021, which was a decrease from the previous season. Run by Mass Audubon, Firefly Watch monitors populations of fireflies nationwide, using citizen science observations. Observation protocols are simple. Count how many flashes you see in three separate ten second periods. I space mine ten minutes apart to get varying levels of darkness, starting just before sunset. We also record the flash pattern (single, double, or triple flash for instance), start and end times, wind, precipitation, and temperature. For good measure, I also record the colors of the flashes. I start at the end of May and depending on how long I keep seeing fireflies, I go until late August or early September. I use the same location every year to track the same population, and try to stick to the same dates every year. This year the dates for my second observation of the week were a day later than last year. I end the season when I go two consecutive observations with no fireflies. The latest I ended was September 26 in 2018. This year I ended on August 24, the first time I didn't make it into September. The last firefly I saw was August 7, so I actually went beyond the two night standard. 2022 saw a decrease of 94 flashes from 2021, nearly a 16% drop. That's close to 30% fewer than 2020, the highest count so far. The charts below show the population trends. Chart 1 shows each year's counts by date and how the number of flashes observed changes within the season. Chart 2 shows each year's total counts side by side.

While I could use rainy nights in 2021 as a partial explanation for the decreased count, I only had rain during one or two observations this year. This summer was abnormaly dry, but not quite a drought. Not enough rain could be a possible cause. Other factors include light pollution, although the amount of light is unchanged year to year, and pesticide use, but I have no way to measure who is using what pesiticides in the neighborhood. One final explanation is that the neighbors cleared some vegetation from their small woodlot in the back yard. I'll continue monitoring and hopefully the negative trend will reverse itself.

Firefly Watch 2021

Just because I haven't been writing this year doesn't mean I haven't been doing nothing this whole time. I completed my 4th season of Firefly Watch. This program is run by Massachusetts Audubon, but anyone anywhere can participate. 

Observation protocols are simple. Count how many flashes you see in three separate ten second periods. I space mine ten minutes apart to get varying levels of darkness, starting just before sunset. We also record the flash pattern (single, double, or triple flash for instance), start and end times, wind, precipitation, and temperature. For good measure, I also record the colors of the flashes. I start at the end of May and depending on how long I keep seeing fireflies, I go until late August or early September. I use the same location every year to track the same population, and try to stick to the same dates every year.

2020 saw an increase over the previous year and 2019 saw a slight decrease, with 2018 being the initial and baseline year. 2021 was the first year to see a significant decline in the number of flashes. Not only was it lower than last year's total, it was the lowest of all four years. In 2020 I counted 708 flashes. In 2021 I counted 593, a 16% decrease. 

I have no explanation for the drop. There were a few more rainy nights when I was doing observations in the previous years, and that may have grounded some of the fireflies. One night early in the season there was a thunderstorm with heavy rain and gusty wind and no one was flying that night. But in the previous three years I counted a grand total of 17 flashes on that date. While rain may account for some missing fireflies, it still leaves quite a void. Hopefully 2022 will see a rebound.

Year by year comparison of flash counts

Flashes by date

Firefly Recap 2020

The 2020 Firefly Watch is complete, and it's time to crunch the numbers. While many science opportunities were cancelled this year because of the coronavirus, standing in my parents' back yard at night was not affected at all. 

I started with this project in 2018 and chose to continue at the same location in order to monitor the same population. Protocol for Firefly Watch is to count the number of flashes in three periods of ten seconds each on the same night. We record the number of flashes, the color of the flashes, the flash pattern (single flash, J shaped, double flash, etc.), and weather data- temperature, wind, cloud cover, and precipitation. I chose to use the same dates every year. I ended observation when after being shut out twice in a row. This year observations ended on September 3, the earliest end date so far.

Observations got off to a slow start this year. By the time I got through the first observation of June, I only had three flashes recorded. By the end of June, things were picking up. Flashes peaked slightly earlier than previous years, and lasted slightly longer. The post-peak crash wasn't as steep this year. Despite the slow start, early finish, and missing two observations because of vacation, the 2020 total number of flashes was the highest of the three seasons I've done Firefly Watch. 2018 had 694 flashes, 674 in 2019, and 708 in 2020. The increases and decreases year to year are slight, and statistically speaking the population is stable. 

I blame the slow start on the weather. My first observation was May 21, which was less than three weeks after our last snow flurry of the season. A warm winter gave way to a cold spring, which probably delayed firefly emergence.

I will credit the coronavirus along with the weather for the higher number of flashes this year. Fireflies prefer a dark night so they can see each other better. Due to the virus, baseball games were cancelled at the park adjacent to my parents' house. No stadium lights, and the lights at the school next door were off late in the season due to school being digital to start the year. There was no rain during any of my observations this year, and that made for better flying weather. No lightning also makes a darker sky.

I am already looking forward to the start of the 2021 season. Observations will be on Fridays and Mondays next year. Three day weekend getaways might have to wait until September, but as long as firefly numbers remain steady or increase, it will be worth the wait.

Species of the Month

The elk rut is upon us, so to that end the Species of the Month for September is the elk. In North America there are four surviving subspecies and two that are extinct. In Eurasia, where it is known as red deer, there are eight subspecies. 

Female elk herd

Scientific name: Cervus elaphus

Kingdom: Animalia (animals) 

Class: Mammalia (mammals) 

Order: Artiodactyla (even-toed ungulates)

Bull elk

Range: Western North America, northern Europe, northern Asia, isolated reintroduced populations in eastern US, introduced populations in Ireland, Argentina, Australia, New Zealand, and Chile

Habitat: Open woodlands

Lifespan: Average 20 years, but difficult to gauge due to hunting

Diet: Grasses, sedges, forbs; woody growth in winter

Predators: Gray wolves, coyotes, mountain lions, bears

Conservation Status: No special protection 

Elk calf nursing

Other Information: The elk is known for the haunting bugle call of the male during the rut. Bugling is used for attracting a mate and advertising territory. Like other horned or antlered mammals, male elk will spar to establish dominance. Dominant males form a harem of females. On occasion, a lesser male will sneak in to mate with one or more of the harem. Elk are social and form segregated herds. Females and calves are dominated by a single alpha female. Males form a bachelor herd. The sexes mingle during the late summer/early fall migration and mating season. Following the birth of calves, mothers and their babies form a separate nursery herd away from the rest of their normal herd. Aside from being larger than deer, elk can also be distinguished by a larger head, dark mane, and large white rump patch. Like deer, elk are most active in early morning and late evening. Coming around a bend on the way to work and seeing the big white butt in the road is a great way to start the day, if given enough stopping distance. Elk browse on grasses and forbs in spring, summer, and fall. Their winter diet may include green woody growth. As ungulates, they have a multi-chambered stomach and chew their cud. Only male elk grow antlers, which they shed annually. Eastern populations of elk were extirpated in the 19th century. Several successful reintroductions of Rocky Mountain elk have since occurred, notably in Elk County, Pennsylvania, and Kentucky.

Bull elk showing off his rump patch

This week's information comes from University of Michigan's Animal Diversity Web. Stay tuned for a recap of the 2020 firefly season next week.

Firefly Watch 2019 Results

Beginning in late May and concluding in September, I conducted observations for Massachusetts Audubon again this year. I count how many flashes I see in three separate periods of ten seconds each. I usually separate those periods by five to ten minutes, to allow for increasing level of darkness. Mass Audubon asks for data other than how many flashes. They also want time and date, weather conditions (cloud cover, precipitation, wind, and temperature), flashing patterns (single flash, double, triple, J-shaped), and color of flashes. Weather may affect firefly behavior, while color and pattern indicate separate species of fireflies.
After two years of submitting observations for my location (my parents' back yard), I don't have enough data to notice any population trends yet. To track population trends, I tried my best to conduct observations on the same dates as last year. This wasn't always possible, like the night I had to chose between fireflies and my daughter's graduation. Guess who won.

Graph of 2018 firefly flashes

Comparing 2018 to 2019, there was a slight decrease in number of flashes but not statistically significant. The first fireflies were seen the same day both years, while the last was seen about a month later in 2018 than in 2019. Peak flashing began almost two weeks earlier in 2019 than in 2018, and following crash was much sharper, without the brief rises that occurred in 2018. My guess is that with a earlier and longer peak, mating was successful and there was no need to keep looking for a date.

Graph of 2019 firefly flashes

What I was told by my mom before I began this project in 2018 was that there weren't really any fireflies around anymore. Since then, I've learned it's not true. She says there are definitely more now, but without any data to back it up I have to take her word for it. I don't remember if there are more or less than when I was a kid. It's not something I was looking at scientifically at the time. I do remember seeing fireflies in September only once before 2018 though. I don't remember what year it was, but I remember they didn't show up until late June, so we had them for the same length of time that I was used to.

Graph showing 2018 and 2019 flashes

Since the end of the season, I moved a few miles away. Despite having to drive a little farther, I will continue observations at my parents' house for consistency. It's hard to establish a trend if I don't use the same location. I may add my new location and start a data set here as well. After getting a second set of data, I am closer to being able to track populations. I am already looking forward to the return of next year's fireflies and the data they'll give me.

Firefly Watch

I participated in an ongoing citizen science project over the summer. Firefly Watch was formerly run by Boston’s Museum of Science, but was run by Massachusetts Audubon this summer, my first with the program. The goal is to monitor firefly populations by counting the number of flashes in three periods of ten seconds. Colors and flash patterns, as well as date, time, weather conditions, and site conditions are all recorded. I signed up for this because fireflies were always a highlight of the summer when I was a kid, and later when my own kid was little. 

Having been away from my ancestral home for a decade, I had no knowledge of local population trends other than my mom telling me she never sees fireflies anymore. That was disturbing to hear. So twice a week I went to my parents’ house starting in late May to see if they had any fireflies left. The first ones showed up on Memorial Day, right about when I remember them first arriving. They were few and far between for the first two weeks or so and peaked around the 4^th of July. I decided to keep up the watch until I had two consecutive shut outs, and expected to be done the first week of September. 

However, the last firefly I recorded was on September 24^th, later than I’ve ever seen one. In fact, I only remember seeing them in September once before, and they came a month late that year. To top it all off, I saw another on September 28^th during the day while away from home. However, to be consistent I only counted observations at one site. To me, it isn’t helpful to track population trends if I am not tracking at the same location, at least in this case. For something larger with a wider range I would, but these little guys don’t roam very far. Since this was my first field season I have no data to compare with, but I plan on being back. Hopefully all I’ll see is positive trends!

Feel free to sign up for Firefly Watch next year!

Blink and You'll Miss it

When I was a kid, summer was my favorite season. No school, great weather, fresh blueberries and strawberries, the smell of freshly cut grass, and endless days of running around in the woods with my friends. Evenings were magical because I could go outside and catch the fireflies. It was easy while there was still some daylight (unless they went higher than my little arms could reach) but as it got darker they became harder to find in between blinks. Looking back, I wonder why I did it. I didn’t do anything with them besides let them walk around on my hand before flying away. The magic returned when I got to watch my daughter chase them around the yard, while my wife watched in bewilderment. Poor thing grew up without fireflies, and alien species in the Northwest.

Traditionally, fireflies (the are actually a beetle, not a fly) first appear right around Memorial Day and vanish just before Labor Day, but I remember one year we had a weird spring and they were a month late. However, they stayed through September to make up for missing most of June. The flashes they give off are the fascinating phenomenon of bioluminescence a living light source. They are trying to find a mate to make the next generation fireflies and keep summer nights full of wonder and amazement.

Firefly dorsal view (Missouri Department of Conservation)

Last year I got a disturbing report from my mom back in the Old Country (Pennsylvania) that she isn’t seeing as many fireflies in recent years. I contacted Christopher Tipping, an entomologist at Delaware Valley University in nearby Doylestown to see if he has been noticing any trends. He told me the same thing I hear about so many other species: habitat loss. He says weather can also be a factor, as I discovered the year they were a month late. 

Firefly in flight, between blinks (Smithsonian Magazine)

Every living thing on the planet requires food, water, air, and a space to call home. Insects are no different. Recall from an earlier Nature Minute I discussed the disappearance of bees, and habitat loss was on the list of suspects. What kind of habitat do fireflies prefer?

While there are many different firefly species (maybe even several in your yard at once) they generally seem to prefer an open area like a meadow or your back yard where they can see each other’s flashes, or forest edges. Larva live in the ground and require moist soil, which in my experience is common in woodlands. There is still much to be learned about how moist they need their soil or how artificial light sources affect their matchmaking skills. 

Enjoy a National Geographic video on fireflies.

Firefly in full blink (Washington Post)

Are you interested in protecting or enhancing your firefly habitat? As a National Wildlife Foundation Habitat Steward, I can help. Together we can keep summer nights magical for kids everywhere. This week's information comes from Christopher Tipping, National Wildlife Foundation, and Firefly Watch.

NWF: https://www.nwf.org/Wildlife/Wildlife-Library/Invertebrates/Firefly.aspx

Firefly Watch: https://legacy.mos.org/fireflywatch/

MO Dept of Conservation: https://nature.mdc.mo.gov/discover-nature/field-guide/fireflies-lightning-bugs

Smithsonian Magazine: http://www.smithsonianmag.com/science-nature/14-fun-facts-about-fireflies-142999290/

Washington Post: https://www.washingtonpost.com/news/to-your-health/wp/2015/07/22/scientists-are-working-with-the-light-of-fireflies-to-improve-medical-diagnoses/?utm_term=.b7d5ed9a0da6