On the Brink: Southwest spring firefly
(Xerces Society)
Globally, there are over 2,000 species of fireflies, a type of beetle (Coleoptera: Lampyridae), with over 170 of these species residing in North America. My days as a child were spent waiting for the sun to go down so I could watch the light show of fireflies (also known as lightning bugs) dot the fields in my front yard.
Sadly, fireflies are on the decline and need our protection. Up to a third of North American fireflies may be at risk of extinction.
(Xerces Society)
The Southwest spring firefly can be found in montane desert habitats and springs in Arizona at elevations ranging from 4000-6000 feet. This includes habitats in the Madrean sky islands and surrounding foothills and stream canyons, where it is associated with marsh areas and other ephemeral habitats along permanent streams, including seeps and areas with standing water.
(Anna Walker)
Occurring in southern Arizona and Sonora, Mexico, this species has been documented from just over two dozen localities, earning it’s name on a list of recent potential endangered species listings. Las Cienegas NCA and Mint Springs, managed by the Bureau of Land Management and Nature Conservancy, respectively, boast the two largest known populations in the U.S.
You can find adults of both sexes flashing their lights from early June through late July near streams and springs. Flashes appear green in color. Larvae feed on snails at night along streambanks, then did themselves into the mud while they pupate.
Firefly larvae use bioluminescence to warn predators of unpalatable steroids they contain, while the adults use bioluminescence both as a form of mate communication and predator avoidance. Many firefly species produce or ingest toxic defense chemicals called lucibufagins to protect themselves from predators, particularly vertebrate predators such as birds.
Why is it at Risk?
Because this species is nocturnal and associated with wetland and riparian habitats, it is threatened by drought, riparian corridor severance, habitat degradation and direct trampling due to cattle, intrusive recreation, light pollution, and hydrological modification for farming, ranching, and copper mining.
Artificial light at night (also known as light pollution or ALAN) negatively affects the reproductive success of nocturnal firefly species that require darkness for their courtship displays. Artificial light at night can interfere with the behavior by confusing them, drawing them to the artificial lights (phototaxis), or blinding them temporarily - much like a deer in the headlights.
The Southwest spring firefly is threatened by habitat loss and degradation due to groundwater depletion and modification of waterways for agriculture, livestock grazing, and mining. Researchers predict that the quality of this species’ habitats will continue to decline within its known range due to climate change and associated drought, which can cause drying of permanent rivers and nearby ephemeral habitats upon which this species depends. More localized threats such as trampling by cattle, water and light pollution, declines in prey species, pesticide use, off-road vehicle use, and other intrusive recreational or tourist activities.
The Morenci Mine—the largest copper producer in North America—is located along the eastern end of the Eagle Creek drainage, one of the two known locations for the firefly.
Several of the known B. w. wickershamorum populations occur within recreation areas, including the Coronado National Forest. Hiking, wildlife viewing, horseback riding, mountain biking, and off-road vehicle (ORV) use are all popular activities within these areas. Because the Southwest spring firefly is vulnerable to trampling and habitat degradation, off-trail hiking and ORV use can be particularly damaging to its populations.
What you can do
Report your Arizona firefly sightings to the Firefly Atlas!
Turn off your outdoor lights at night so the lights of this firefly aren’t diminished by light pollution. You can read more about firefly-friendly lighting in our fact sheet. Join the Globe at Night Citizen Science project to measure artificial light near you.
Avoid pesticide use, which could harm this firefly, its habitat, or its prey.
Reduce cattle use near their habitats, like wetlands and springs.
Reduce off-trail use in areas where the firefly lives.
