Observation: Photuris frontalis
Primary Observer:
Mary Patterson
Event Date:
2026-06-30
Status:
Verified
Survey
Site Name:
Mill Creek Falls Nature Preserve #4
Province/State:
Pennsylvania
Event Date:
2026-06-30
Time of Day:
Night-Time
Start Time:
21:00
End Time:
22:30
Number of Observers:
2
Primary Observer:
Mary Patterson
Additional Observers:
Ross Patterson
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:
trail along a stream deep in woods, high hills on either side of stream
Elevation (meters):
119
Area Searched (hectares):
2
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:
2-10
genus:
photuris
Species:
frontalis
Observation Notes:
Has something laid eggs on this firefly? What are the two red ovals under wings and on the body?
A very energetic firefly!!
Specimen Voucher Number:
Flash Behavior
First Flash Time:
21:30
Last Flash Time:
22:30
First Flash Temp (F):
79
Last Flash Temp (F):
79
Flashes in Pattern:
>4
Flash Color:
Orange
Flash Pattern Period:
continual
Flash Duration:
1
Flash Interval:
.5
Male Height Zone:
Low (0-3 ft)
Flash Location:
riparian area and trail at about shoulder height
Male Flash Behavior:
Female Flash Behavior:
3 thoughts on “Observation: Photuris frontalis”
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Mary, this is a very exciting find! The firefly you photographed is a male snappy single sync (Photuris frontalis), a synchronizing firefly that– to my knowledge– had not been documented in PA. Unlike most Photuris species, Photuris frontalis has a unique appearance: a clear pronotum with a dark/brown hourglass marking in the center (no red or pink), a dark underside and legs, stigmatiform pits in the light organs (lacking in Photuris in the versicolor group)
The red things on its back are mites.
A few notes about flash pattern:
The snappy single sync is has a single-pulse flash pattern. That is, the unit of blinks that predictably repeats is a single flash. However, this species will emit its flash pattern continuously for long periods, sometimes giving the impression that it is a multi-pulse flasher because the flash pattern period (time between the start of one flash and the start of the next flash) is so short.
The flash duration is how long each blink of light lasts. In the case of Photuris frontalis, the duration is so short it’s not practical to measure in the field: 0.1 seconds or less!
The flash interval and flash pattern period are essentially the same in this case: let’s say 1 second for the flash pattern period and 0.9 seconds for the flash interval.
Congratulations on this observation! I will be updating the filterable species checklist to include PA in the distribution of this species.
Richard-
This is SUPER EXCITING!! I don’t remember – did I have this ID correct or did you adjust after review? My 13 year old grandson was helping me to determine species based on my observations. I told him we had contributed to firefly science – he thought that was super cool!! Never when I started this project did I think I would find anything fresh or new. But, I do remember standing in that area and said to my husband, these are different, not like anything else we have seen. And, that if we had any sycronous in this area this would be the habitat – it is super, super, super dark and the land is so steep on either side of the creek that the land has not been disturbed, even historical logging would have been difficult. Anyway, I have shared this with my boss. We have a staff meeting tomorrow and hopefully I have the opportunity to share.
Thank you so much!!
Mary Patterson
Congratulations on this identification. Your description is spot on and your photos are amazing. We look forward to you finding more.