Summer heat and humidity aren’t the only things that arrived early this year. Early last week, Capital Weather Gang commenters reported their first firefly spottings of the season:
snowlover31: Saw the flash of a firefly about 30 minutes ago.....
Camden-Capital Weather Gang: That is pretty early. Even last year I don’t remember them birthing this soon, even with incredible heat early-on!
Camb67: I saw one on Thursday at work. I thought it was pretty early too.
Bombo47jea: First firefly...found a female outside my condo an hour or two ago. No males seen flashing yet.
walter-in-fallschurch: i don’t really recall much about fireflies, ‘cept that it’s a deep-into-summer thing in my mind.. i always associate fireflies w/july/august.
Like walter-in-fallschurch, most of us probably equate fireflies - also known as “lightning bugs,” though they are bioluminescent beetles rather than true bugs - with mid-summer nights. Indeed, the peak season in the D.C. area is typically mid-to-late-June and early July. But in past years, we may have seen a few lone flashes as early as early May, and a warming climate has fireflies along with many other insects appearing earlier in the year than they used to.
Recent trends also suggest fireflies may be increasing, at least locally, not long after scientists feared they might be disappearing.
Fireflies flash to attract mates - a process that has been innocently interrupted by many a glass jar and bug net over the centuries. Once an adult emerges from a pupa, it has only a few weeks to find a mate before it dies (flashing its luminescent lanterns doesn’t always work: more than 50 percent of males will die without ever having mated).
Each species flashes a specific color at a certain interval. Males fly above ground and signal to females that are perched on blades of grass or bushes below. If she likes his light, she signals back, they mate, and soon after she lays her eggs (wouldn’t life be easier if all we had to do to find a mate was flicker a flashlight?).
Like many outdoor insects, fireflies’ life cycles are triggered by environmental cues. For example, as air temperature warms, flashes accelerate (mid-70s to mid-80s are ideal). Also, firefly eggs can only survive in moist soil, eliminating most of the western United States as potential breeding ground. Wet springs can contribute to higher firefly populations. Larvae can survive winters underneath snowpack, as long as a warm, humid summer follows. Researchers in Great Smoky Mountains National Park have even begun to analyze degree-days in order to predict peak firefly season for tourists (study).
The ‘Fireflies’ song by Owl City reached No. 1 on the Billboard Hot 100.
Because they are so in sync with their environment, fireflies and many other insects are especially good indicators of regional climate change.
“The earlier timing of insect appearance is now a fairly well-guided phenomenon in the [insect] world,” said Michael Raupp, professor of entomology at the University of Maryland. Scientists have observed that many different insect species - from pollinators to pests - are now appearing weeks earlier in the year, following warmer cues from the environment. “It’s a broad-scale phenomenon across the country,” he said.
Every year, Raupp notes the first firefly appearance on his Bug of the Week website. Fireflies are now appearing one week earlier than when he began his observations in 2005.
The seasonal cycles of problem species such as the gypsy moth have been studied extensively, yet very little official research has been done on the timing and numbers of fireflies. To bridge this gap, the Boston Museum of Science began the Firefly Watch citizen science program in 2008 to monitor and record firefly flashes in the eastern United States (the project has also teamed up with the National Children’s Museum to bring the project to the Washington area -- see www.readysetglow.org to get involved).
The data collected will provide scientists with more information about the timing of firefly mating seasons. It will also help them keep tabs on populations that have been largely impacted by light pollution and habitat loss due to urban sprawl.
“Through the latter years of the 2000s, fireflies were down in this region,” said Raupp. But based on last year’s abundant numbers and this year’s weather, Raupp predicts the summer 2011 numbers will be the same if not better than last year. - a trend he terms the “renaissance of lightning bugs.”
What’s the firefly status in your neck of the woods (or streets)? Have you seen any flickering yet this year, and if so, does it seem earlier than past years? Leave a comment below.