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Observation: Photinus pyralis
Primary Observer:
Carl Manthey
Event Date:
2025-07-19
Status:
Verified
Survey
Site Name:
Great Marsh, Elverson, PA
Province/State:
Pennsylvania
Event Date:
2025-07-19
Time of Day:
Night-Time
Start Time:
20:30
End Time:
22:00
Number of Observers:
8
Primary Observer:
Carl Manthey
Additional Observers:
Kathy Varaday, Christa and Trip Tyner, John Lisowski, Meredith Heffner, Myrna Villanueva, Melinda Siegel
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:
Elevation (meters):
150 - 200
Area Searched (hectares):
9
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:
Flashing
Number Observed:
50+
Genus:
Photinus
Species:
pyralis
Observation Notes:
This firefly species was observed by all three teams throughout the Great Marsh property but was most frequently documented proximal to the house, guest house and nature center due to it's early flash time corresponding to the start of the survey. The earliest flashes were over mowed grass areas, but the flash area expanded to marsh, meadow, soybean fields, and shrub/tree-line as darkness deepened.
Specimen Voucher Number:
Flash Behavior
First Flash Time:
20:30
Last Flash Time:
22:00
First Flash Temp (F):
76
Last Flash Temp (F):
74
Flashes in Pattern:
1
Flash Color:
Yellow
Flash Pattern Period:
6 sec
Flash Duration:
~0.75 sec
Flash Interval:
5 sec
Male Height Zone:
Low (0-3 ft), Moderate (3-8 ft)
Flash Location:
These fireflies exhibited the classic flash behavior of a long flash every 6 seconds rising out of the grass at or before sunset followed by flashes at or about eye level after dark. On July 19th, this species was the most frequently observed
Male Flash Behavior:
A long flash every 6 seconds rising out of the grass at or before sunset followed by flashes at or about eye level after dark.
Female Flash Behavior:
1 thought on “Observation: Photinus pyralis”
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Thanks for this observation! Very nice documentation of big dipper fireflies.