Observation: Photinus pyralis
Primary Observer:
Roger
Event Date:
2025-07-01
Status:
Unverified
Survey
Site Name:
Undisclosed
Province/State:
Illinois
Event Date:
2025-07-01
Time of Day:
Night-Time
Start Time:
21:10
End Time:
21:20
Number of Observers:
1
Primary Observer:
Roger
Additional Observers:
NA
target_species_genus:
photinus
target_species_species:
pyralis
Location and Habitat
Location Accuracy (meters):
>1000
Habitat Type:
Developed - Sub/urban areas; parks/gardens
Habitat Type Notes:
Developed city neighborhood, lots of trees and bushes and some wild, undeveloped areas
Elevation (meters):
623
Area Searched (hectares):
1
Artificial Light Sources
Vehicles: No
Street Lights: No
Buildings: Yes
Street Lights: No
Buildings: Yes
Artificial Light Types
Sky Glow (diffuse illumination in the sky): Yes
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:
11-50
genus:
photinus
Species:
pyralis
Observation Notes:
This was a bit later than when I normally check rigth at sunset. It was darker but there were still a good number visible. In my first count I counted 23 and a bait later it was 25
Specimen Voucher Number:
Flash Behavior
First Flash Time:
21:15
Last Flash Time:
21:25
First Flash Temp (F):
78
Last Flash Temp (F):
78
Flashes in Pattern:
1
Flash Color:
Yellow
Flash Pattern Period:
1
Flash Duration:
1
Flash Interval:
3-10 seconds
Male Height Zone:
Low (0-3 ft), Moderate (3-8 ft)
Flash Location:
most were flying, 3-6 feet above mowed grass, some in more wooded areas
Male Flash Behavior:
Random single flashes
Female Flash Behavior:
1 thought on “Observation: Photinus pyralis”
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Thank you for submitting this firefly observation! Without a photo of the firefly, it is tricky confirm with certainty that this was big dipper fireflies (Photinus pyralis), but the urban habitat, relatively low flashing height and early evening display period are a good fit for the species.
A note about flash pattern terminology, for next firefly season:
“Flash pattern period” refers to the number of seconds between the start of a flash pattern and the start of the next repetition of that flash pattern. For example, the big dipper firefly (Photinus pyralis) typically has a flash pattern period of 5-7 seconds.
“Flash duration” is how long each flash lasts. Usually this is too fast to measure accurately, but you can estimate whether it is more or less than 0.5 seconds, you can enter “not recorded,” or you can do a verbal description (such as “very brief”).
“Flash interval” refers to the time between the end of one flash and the beginning of the next. In species with single flash patterns and short flash durations, this is basically the same as “flash pattern period,” just a little shorter.