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Observation: Photinus pyralis
Primary Observer:
Caitlin
Event Date:
2025-07-06
Status:
Unverified
Survey
Site Name:
Hackettstown 2
Province/State:
New Jersey
Event Date:
2025-07-06
Time of Day:
Night-Time
Start Time:
20:31
End Time:
21:15
Number of Observers:
2
Primary Observer:
Caitlin
Additional Observers:
Target Species Genus:
unknown
Target Species Species:
unknown
Location and Habitat
Location Accuracy (meters):
0-25
Habitat Type:
Riparian - Areas Along lake or stream
Habitat Type Notes:
Detention basins and rivers nearby in wooded but residential area
Elevation (meters):
600
Area Searched (hectares):
Artificial Light Sources
Vehicles: Yes
Street Lights: Yes
Buildings: Yes
Street Lights: Yes
Buildings: Yes
Artificial Light Types
Sky Glow (diffuse illumination in the sky): Yes
Light Trespass (light cast on surfaces beyond its intended target): Yes
Glare (bright light causing visual discomfort): No
Light Trespass (light cast on surfaces beyond its intended target): Yes
Glare (bright light causing visual discomfort): No
Artificial Light Notes:
Observation
Observation Type:
Flashing
Number Observed:
50+
Genus:
Photinus
Species:
pyralis
Observation Notes:
*photo provided was from observation on 07/04, but ones seen on 07/06 looked similar.
Specimen Voucher Number:
Flash Behavior
First Flash Time:
20:31
Last Flash Time:
21:15
First Flash Temp (F):
79
Last Flash Temp (F):
78
Flashes in Pattern:
1
Flash Color:
Yellow
Flash Pattern Period:
1
Flash Duration:
1
Flash Interval:
15
Male Height Zone:
Moderate (3-8 ft)
Flash Location:
In trees, bushes, on the ground, and in the air.
Male Flash Behavior:
Female Flash Behavior:
2 thoughts on “Observation: Photinus pyralis”
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Thank you for submitting this firefly observation! Based on the photo and flash pattern of single, yellow flashes at dusk, this is definitely a firefly in the genus Photinus, and Photinus pyralis would be the most likely species.
A quick note about flash pattern details:
“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, 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, but”
Thank you so much! In looking up the species, it does seem like Photinus pyralis is most likely, as they’re described to light up in a “J-shaped” pattern which I recall them doing now. Thanks for the explanations on the flash patterns/duration/interval.