Firefly population beginning to dim
Fireflies light up the Hill Country during summer nights and contribute to an enchanted atmosphere, but a Texas Certified Master Naturalist said they are on the decline. Firefly Conservation and Research Founder Ben Pfeiffer, a group that supports firefly research, conservation and public knowledge, was a guest on Texas State University’s Big Ideas podcast to discuss the flying insect and threats to their existence.
Pfeiffer said the flash, which is the glow emanated by the insect, is caused by a chemical reaction that occurs, ignited by the introduction of oxygen when the insect inhales, between two compounds luciferase, an amino acid, and luciferin, an enzymatic catalyst. He said it will charge then release photons of light in a repetitive process.
The firefly does not flash just for our entertainment.
“It’s a form of sexual selection essentially,” Pfeiffer said. “Females are attuned to certain differences between male flash timing … What the female is looking for is basically males that have longer flashes or faster flash rates.”
Firefly populations are declining, and Pfeiffer said this is due to multiple factors, including drought, light pollution, environmental contamination, habitat degradation and habitat loss— the largest contributing factor.
“It’s unfortunate that we live in an area that’s really beautiful, but also is experiencing one of the largest disappearances of native habitat in the state,” Pfeiffer said. “It is being replaced by subdivisions and development, and a lot of times those areas are cleared to the bedrock level.”
Pfeiffer said this time of year has major implications for the fireflies that will be seen in the spring and summer.
“In the lifecycle of a firefly, they spend most of their time in the larval state,” Pfeiffer said, adding that there is rapid growth during that stage and the larvae are constantly eating. “During December in Texas, sometimes we’ll get seasonal rains, essentially. Those fireflies are preparing to hibernate, in a way, and they’re in a growth stage that they're months away from pupation, like five or six months. And December, this time period right now, it’s just really helpful for them, before it gets too cold, to just eat as much as possible … In my research, if you get a really good seasonable wet winter that’s mild that produces a really good firefly year.”
Pfeiffer said this area had several freezes over the last two years that likely killed a lot of the larva, which is the reason for the sparse amount of fireflies this past summer.
“The food that fireflies need to eat also gets killed off,” Pfeiffer said. “So if the snails and the slugs and the worms and little small insects disappear, then the larvae don’t have much to eat.”
Pfeiffer is predicting a small firefly population next year as well but stresses that there will still be fireflies around— just fewer than usual.
“This summer was really brutal,” Pfeiffer said. “Just because of how hot it’s been and the seasons that we’ve had [might contribute to fewer fireflies this coming summer].”
Pfeiffer said although there are declining populations, Texas has the highest diversity of firefly types compared to other states in the United States.
“Those include diurnal, night time flying, and also daytime species as well,” Pfeiffer said. “Then you’ve got different genuses and families and those all have different characteristics, and Texas … has many diverse ecoregions. That has created some elements for speciation to occur— just lots of neat and cool habitat specific fireflies to occur.”
Pfeiffer said the Edwards Plateau Region of the Hill Country, which includes San Marcos, has several endemic species. “We have Photinus Concisus, which is an endemic species [that] just occurs here in the Hill Country, goes all the way to Val Verde County and then a few counties upwards,” Pfeiffer said, adding that there is a species of Pyractomena Angulata that can be found locally and will flash a bright amber color. “We’ve got some other really cool species like Photuris Bill Brown Eye, which is a firefly that will synchronize its flash in large groups. It has a double twinkle flash, and it likes to fly around treelines.”
To learn more about fireflies go to www.firefly. org/ and to listen to the podcast go to news. txs t . edu/ inside- txst / big-ideas-podcast/episode- 46.html.
