Observation: Unknown
Primary Observer:
Carl Manthey
Event Date:
2025-06-21
Status:
Unverified
Survey
Site Name:
Great Marsh, Elverson, PA
Province/State:
Pennsylvania
Event Date:
2025-06-21
Time of Day:
Night-Time
Start Time:
20:30
End Time:
22:00
Number of Observers:
4
Primary Observer:
Carl Manthey
Additional Observers:
Bernard Brown, Myrna Villanueva, Diana Cormack
target_species_genus:
unknown
target_species_species:
unknown
Location and Habitat
Location Accuracy (meters):
500-1000
Habitat Type:
Open Freshwater Wetland - Wetland Bog, fen, freshwater marsh
Habitat Type Notes:
Habitat is highly variable. Land was originally a large marsh. It was briefly drained and used as a dairy farm until the 1950s. At that time, it was allowed to revert to a marsh, although a number of ponds were built. The area viewed includes wet marsh with cattails, ponds with spatterdock, swamp with black willow, wet meadows with native perennials, mowed grassy paths, and higher ground with red maple, black cherry, spicebush, and oak. There are also a couple soybean fields and a sheep pasture.
Elevation (meters):
150 - 200
Area Searched (hectares):
7
Artificial Light Sources
Vehicles: No
Street Lights: No
Buildings: No
Street Lights: No
Buildings: No
Artificial Light Types
Sky Glow (diffuse illumination in the sky): No
Light Trespass (light cast on surfaces beyond its intended target): No
Glare (bright light causing visual discomfort): No
Light Trespass (light cast on surfaces beyond its intended target): No
Glare (bright light causing visual discomfort): No
Artificial Light Notes:
Observation
Observation Type:
With Flash Data
Number Observed:
50+
genus:
unknown
Species:
unknown
Observation Notes:
The evening began with strong shows of Photinus pyralis over mowed areas with increasing firefly diversity and numbers as darkness settled in between 9:20 and 10 PM. By 10 PM the "lightshow" was intense and magical over marsh, wet meadow, and even over the soybean fields. We saw many flash patterns but were able to catch and photograph only a few fireflies. Some of the flash patterns that are unaccompanied by specimens include:
1) tiny erratic brief flash once every 3 seconds (5 flashes in 14 sec) at eye level,
2) brief flash nearly every second (5 flashes in 7 seconds),
3) longer rising flashes every 3.3-4 seconds,
4) quick doublet or triplet flicker flashes in trees every ~5 seconds,
5) quick strobe-like flashes every 0.67 sec (9 flashes in 6 sec),
6) bright flashes every 3.3 seconds (5 flashes in 17 sec), and
7) bright streaks while flying fast (rare and hard to measure).
Specimen Voucher Number:
Flash Behavior
First Flash Time:
21:15
Last Flash Time:
22:00
First Flash Temp (F):
78
Last Flash Temp (F):
78
Flashes in Pattern:
1
Flash Color:
Unknown
Flash Pattern Period:
various
Flash Duration:
various
Flash Interval:
various
Male Height Zone:
Low (0-3 ft), Moderate (3-8 ft), High (over 8 ft)
Flash Location:
grass, meadow, marsh, shrubs, trees
Male Flash Behavior:
The evening began with strong shows of Photinus pyralis over mowed areas with increasing firefly diversity and numbers as darkness settled in between 9:20 and 10 PM. By 10 PM the "lightshow" was intense and magical over marsh, wet meadow, and even over the soybean fields. We saw many flash patterns but were able to catch and photograph only a few fireflies. Some of the flash patterns that are unaccompanied by specimens include:
1) tiny erratic brief flash once every 3 seconds (5 flashes in 14 sec) at eye level,
2) brief flash nearly every second (5 flashes in 7 seconds),
3) longer rising flashes every 3.3-4 seconds,
4) quick doublet or triplet flicker flashes in trees every ~5 seconds,
5) quick strobe-like flashes every 0.67 sec (9 flashes in 6 sec),
6) bright flashes every 3.3 seconds (5 flashes in 17 sec), and
7) bright streaks while flying fast (rare and hard to measure).
Female Flash Behavior:
1 thought on “Observation: Unknown”
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Sounds like an awesome (and overwhelming) show! My guess is that the dominant flashes were Photuris fireflies but that there could have been Pyractomena and Photuris in the mix, too.