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Observation: Photinus pyralis
Primary Observer:
Carl Manthey
Event Date:
2025-06-07
Status:
Unverified
Survey
Site Name:
Great Marsh, Elverson, PA
Province/State:
Pennsylvania
Event Date:
2025-06-07
Time of Day:
Night-Time
Start Time:
20:30
End Time:
22:00
Number of Observers:
5
Primary Observer:
Carl Manthey
Additional Observers:
Myrna Villanueva, Bernard Brown, Diana Cormack, Kathy Varady
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):
8
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:
1
Genus:
Photinus
Species:
pyralis
Observation Notes:
Single brief flash every 5 seconds 1 ft over mowed lawn next to a sheep pasture. Flash pattern suggested P. marginellus, but pygidium suggested P. pyralis.
Specimen Voucher Number:
Flash Behavior
First Flash Time:
20:45
Last Flash Time:
20:50
First Flash Temp (F):
71
Last Flash Temp (F):
71
Flashes in Pattern:
1
Flash Color:
Yellow
Flash Pattern Period:
5
Flash Duration:
<0.5
Flash Interval:
5
Male Height Zone:
Low (0-3 ft)
Flash Location:
This was a single firefly flying low to the ground over mowed lawn. This was the first flashing firefly of the night.
Male Flash Behavior:
Single brief flash every 5 seconds 1 ft over mowed lawn.
Female Flash Behavior:
1 thought on “Observation: Photinus pyralis”
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Thanks for submitting this observation! You are wise to consider Photinus marginellus as a possibility, based on the location and flash pattern. I would still lean toward Photinus pyralis based on overall appearance. Size can be very helpful in cases like these, as the body length for P. marginellus is about 6-9 mm, while the body length for P. pyralis is about 9-15 mm.