Photo: Common Eastern Firefly, Judy Gallagher
Judy Gallagher is an ASNV board member and a regular surveyor of local wildlife who also captures photos of what she sees, in particular the less common species.
Pyractomena species firefly larva, Judy Gallagher
I don't particularly like winter. It tends to be dreary and there aren't many insects to distract me. But if I look hard enough, I can find a few signs of life. One of the earliest insects I see each year is the larva of the Spring Treetop Flasher, Pyractomena borealis, a firefly or lightning bug. Despite the names, fireflies are not flies and by entomologist definitions, they also are not bugs. They are beetles in the Lampyridae family. There are more than 100 North American firefly species, and more than 2,000 species world-wide.
The Spring Treetop Flasher larva eats slugs and earthworms, and sometimes cooperatively hunts its prey with other larvae. Like its adult version, the larva is bioluminescent.
Pyractomena species firefly pupa, Judy Gallagher
But at this time of year, the Spring Treetop Flasher larva creeps slowly along the trunks of tall trees, looking for a place to pupate.
Spring Treetop Flashers - Pyractomena borealis mating, Judy Gallagher
Adult males tend to emerge before females, and sometimes stand guard over the female pupa, mating with her as soon as she emerges. These are among the first fireflies to flash in our area, starting as early as late March. They usually display high in the trees from about 45 minutes to 90 minutes after sunset, but only on relatively warm dry nights.
The larva of all firefly species glow and some species have eggs that glow, but not all adult firefly species produce light. Those species that blink as adults do so to attract mates, but bioluminescence likely evolved as a warning to predators that fireflies are toxic. Firefly adult lights can be slightly different-colored based on species, with Photuris species being slightly green, Photinus species slightly yellow, and Pyractomena species ranging from a more deep yellow to orange or amber. The colors correspond to the time of night when the fireflies are out, with yellow being more visible near dusk, and green flashes being more easily seen later at night. Light pollution can negatively impact the effectiveness of the fireflies’ blinking.
Winter Firefly - Ellychnia corrusca, Judy Gallagher
The Spring Treetop Flasher is not the only firefly species that can be seen now. The Winter Firefly, Ellychnia corrusca, is out even earlier in the year. Adults mature in the fall or winter and disperse and mate in mid-March to early April. They can survive freezing temperatures, but are only active when it is above freezing. They defend themselves with toxic chemicals that ooze from the edges of their wing covers. These fireflies don't flash.
Sneaky Elf - Pyropyga decipiens, Judy Gallagher
Another local species that doesn't flash is the Sneaky Elf, Pyropyga decipiens. It is active during the day and is usually found in tall grass, gardens, and waste areas. Like many other beetles, it pretends to be dead as a defense mechanism. Predators find dead insects to be uninteresting or unappetizing and leave them alone.
Common Eastern Firefly - Photinus pyralis, showing its "lantern", Judy Gallagher
The Common Eastern Firefly, also known as the Big Dipper, is the firefly that you would typically see flashing in your yard in mid-June through early July. The males usually fly at waist height around dusk and then fly higher up as it gets darker. Because they fly early in the evening, they are less susceptible to the effects of light pollution than most other firefly species that flash.
Photuris species , Judy Gallagher
Most firefly species have a unique flashing pattern that attracts others of the same species. But Photuris species females can mimic the flashing patterns of other species, luring them closer, and then eating them. Photuris species females are also known for eating their male counterparts. The females get defensive chemicals from their firefly prey, which they bequeath to their eggs to give them additional protection from predation. It is difficult to identify Photuris to species level.
Other firefly species adults eat nectar or pollen, and some species adults don't eat at all. Pollen feeders can be effective pollinators.
Fireflies were once collected for the chemicals that make them glow, luciferin and luciferase. These chemicals are used in medical applications such as cellular imaging and determining enzyme activity. Fortunately for the fireflies, synthetic chemicals can now be produced in laboratories.
Including the larvae that I mentioned earlier, it is possible to see fireflies here in every month of the year. I am making it a personal challenge in 2024 to see at least one firefly each month.
View more of Judy’s Observations from Meadowood articles here.