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.