Observation: Photuris

Observation: Photuris

Primary Observer:

Jill Gorman

Event Date:





Site Name:




Event Date:


Time of Day:


Start Time:


End Time:


Number of Observers:


Primary Observer:

Jill Gorman

Additional Observers:

Tim Gorman

Target Species Genus:


Target Species Species:


Location and Habitat

Location Accuracy (meters):


Habitat Type:

Woodland/Forest - Trees dominant, and in the over-story

Habitat Type Notes:


Elevation (meters):


Area Searched (hectares):


Artificial Light Sources

Vehicles: No
Street Lights: No
Buildings: No

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

Artificial Light Notes:



Observation Type:


Number Observed:






Observation Notes:

Many greenish flashes of varying speed, duration and shape. Most flashes were rapid with a lot of movement, but some were slow with not much movement. I'm not sure if these are all the same species, but I was only able to capture 1 green flashing firefly. After capture, it flashed rapidly in the insect net and a video is posted at https://drive.google.com/file/d/1O1fPDC3JMsVZIvPTJatUshd7Q9XAMAg8/view?usp=sharing incase that information is useful. I am trying to identify the one or multiple species that I have in my backyard.

Specimen Voucher Number:

Flash Behavior

First Flash Time:


Last Flash Time:


First Flash Temp (F):


Last Flash Temp (F):


Flashes in Pattern:


Flash Color:


Flash Pattern Period:

0.5-1 sec

Flash Duration:


Flash Interval:


Male Height Zone:

High (over 8 ft)

Flash Location:

Most flashes were high up in the trees, except for the low flashing one that we were able to capture. It was flying about 6 ft of off the ground and flashing rapidly in a straight line.

Male Flash Behavior:

Some seemed to travel rapidly in a straight line while flashing while some flashed rapidly while flying in a curved line. Photos appear as a line of dots with a trail. All photos are 10 second exposures.

Female Flash Behavior:


2 thoughts on “Observation: Photuris”

  1. Thank you for submitting this incidental firefly observation! And nice job getting these photos!
    This is a firefly in the genus Photuris, which we can tell based on the long legs, intricate arrow-shaped black marking on the headshield (pronotum), and the hunched posture (the shoulders are higher than the head).

    Based on the shape of the lanterns, we can tell that this is a female Photuris. The lanterns are “flying saucer” shaped, whereas in a male they would fill the whole abdominal segment and be roughly rectangular.

    Because this Photuris is female, we aren’t able to use her flash behavior to help with species ID. It is generally the male courtship flash patterns that are most helpful with identification. Photuris females can flash when in distress, in response to a potential mate, or when imitating flash patterns of other species in order to hunt them!

    In your long exposure photos, you managed to capture what we call “crescendo flashes.” These are shaped like comets, because the firefly’s flash begins dimly, builds in brightness, and then stops abruptly.

    Based on the crescendo flashes and the large size of the female you caught (is the grid size in the photographs 5mm?), my guess is that you were seeing Photuris lucicrescens, also called “July Comets” or “Big Scaries” in Lynn Faust’s field guide.

    • Thank you so much for all of the information! I am just starting to learn and realizing that I know nothing about the complexity of fireflies! I am happy that my photos were good enough to identify this beautiful female. Yes, the grid size is 5 mm and I will be sure to note that on future observations. I look forward to continuing to document the fireflies in my yard, so please let me know if I should try to capture any other types of photos.

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