Firefly Flash Patterns

In Great Smoky Mountains National Park, there are two groups of fireflies. The first group does not flash at all and is active during the day rather than at night. This group includes six species of fireflies. The second group, with about 13 species in the park, uses a pattern of light producing flashes to find and recognize each other. The timing and pattern of these flashes is unique for each species.

Park visitors may see several different species of fireflies during the early summer, when male fireflies use flashing to court females. The pattern of flashes of some of the common firefly species encountered in the park are illustrated and described below.

Firefly flash patterns commonly seen in the park:

 

 

1. Phausis reticulata – This tiny black firefly is common throughout the southeastern United States and is known as the “blue ghost” because males do not flash, but glow with a pale blue or green light. The display lasts for 30-40 seconds with numerous individuals displaying over a large area and is repeated after a brief pause. The blue ghost begins displaying at full dark, about 9:30 pm. Females of the blue ghost are white or pale yellow in color and lack wings.
   
   
2. Photinus brimleyi – The pattern for this species is a series of single flashes of yellow light spaced at intervals of 10 seconds or longer. The display starts at dusk, about 9:30 pm. The distribution of this firefly is spotty in the park and displays occur in open woods. Females lack wings and respond to the male flash with a single flash from the forest floor.
   
   
3. Photinus macdermotti – The pattern for this species is a double flash of yellow light with the two flashes about 1½-2 seconds apart with a brief 4-5 second pause and a repeat of the double flash. This species begins displaying at about 8:30 in the evening and is finished displaying by about 9:30 pm. It is found throughout the park and usually displays in open woods.
   
   
4. Photinus carolinus – This is the “synchronous firefly.” The pattern is a series of 5-8 flashes of yellow light, with all individuals in an area displaying this pattern. This is followed by a period of darkness for 8-10 seconds. The synchronous stopping and starting of the flash sequence displayed by this firefly is unique. The large and spectacular displays of this firefly, which may include thousands of individuals, start at full dark, about 9:30 pm, and displays continue until about midnight. Although the synchronous fireflies in the park have attracted a great deal of media attention, this firefly can also be seen in many areas outside the park. It displays in woods with little understory or at the edge of moist wooded areas.
   
   
5. Photuris spp. – The genus Photuris is represented in the park by at least three species. The pattern of display for this group is a series of single flashes of white light similar to that produced by a flash bulb. These species prey on fireflies of the genus Photinus attracting males by mimicking the flash response of the females, and then catching and eating males they attract.
   
   
6. Photinus pyralis – This species is distinctive with the male flying upwards while flashing a single sustained yellow light, often in the shape of the letter J. This species begins displaying at about 8:30 in the evening before full dark, and is typically finished displaying by 9:30 at night. It is found throughout the park and usually displays in open areas.