Firefly Observations in Northern Michigan
The following video and still images, recorded July 10–17, 2025 in a marsh near Elk Lake, Antrim County, Michigan, document fireflies exhibiting potential synchronous flashing behavior. Activity declined within 5–7 days of the initial observation.
Observation Details
Video description: Clips from three different observations showing flashing in a section of habitat. The video perspective covers approximately ~20 ft (6m) across and depicts a section of a larger area that was observed (~1,600 m²). The first clip was on the evening with the most activity and shows the activity increasing and then waning repeatedly. Clips #2 and #3 were captured later in the week and show less activity, though some apparent synchronization is visible. Clip #2 depicts some of the simultaneous flashing that occurred, as well as a fainter slower flashing in the grass on the right side of the frame.
Dates recorded: 2025-07-10 to 2025-07-17
Time: Approx. 22:00-24:00 EDT (~1-3 hours after sunset)
Location and habitat: Open, grassy marsh area and surrounding old growth forest near Elk Lake in Antrim County, Michigan. Exact coordinates are omitted here to protect a sensitive habitat located on private land. Contact Matt for more information.
Habitat: Open, grassy marsh surrounding a shallow pond (1–2 ft depth), bordered by shrubs, fallen trees, mixed evergreen growth and birch trees. Area is part of a property preserved and undeveloped for 100+ years.
Environmental Conditions: Nights of observation were calm, humid, and slightly warmer than usual (~24 °C/75 °F)
Flashing height: Primarily between 2–10 feet above vegetation
Flashing pattern: Each firefly produced 6–10 rapid pulses (each ~0.5 s), followed by ~6–8 s dark intervals. Some clusters displayed near simultaneous flashing. Ground-level individuals with longer, slower glows and apparent greener hue were observed.
Duration of activity: Began ~30 minutes after sunset and continued for at least 3 hours.
Single 60-second exposure reveals the trails of 6–10 flashes above the grasses and marshy area surrounding a shallow pond. During the observation, clusters of fireflies appeared to flash in waves of approximately 6–10 pulses, followed by a 6–8 second pause before repeating.
Single 91-second exposure revealing the trails of 6–10 flashes.
Single 65-second exposure of vegetation and night sky with fireflies. Distinct flash trails appear above grasses and low shrubs in the background. A single faint flash is visible in the foreground grass, dimmer and steadier than the rapid bursts of 6–10 flashes produced by fireflies flying overhead.
Collected Specimens
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Specimen A, Dorsal
Captured mid-flight during a flash burst. Released post-documentation.
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Specimen A, Ventral
Captured mid-flight during a flash burst. Released post-documentation.
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Specimens A and B
Captured mid-flight during a flash burst. Released post-documentation.
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Specimens A and B
Captured mid-flight during a flash burst. Released post-documentation.
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Specimen C
Captured mid-flight during a flash burst. Released post-documentation.
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Specimen C
Captured mid-flight during a flash burst. Released post-documentation.
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Specimen D
Captured flashing in grass. Released post-documentation.
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![Specimen D]()
Specimen D
Captured flashing in grass. Released post-documentation.
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![Specimen E]()
Specimen E
Captured mid-flight during a flash burst. Released post-documentation.
Several individuals were temporarily captured, photographed, and released. Images include dorsal and ventral views where possible, along with observational notes. Specimens A, B, C and E were caught in flight while flashing. Specimen D appears to be distinctly different in appearance and was caught in the grass.
Location Note
Specific location coordinates are omitted here to protect a sensitive habitat located on private land. Contact Matt Spaulding for more information.
