April 2015 Featured Paper

"Flash Behavior of a Nova Scotian Firefly, Photuris fairchildi, during Courtship and Aggressive Mimicry," by Lawrent L. Buschman.
The Coleopterists Bulletin, Vol. 28, No. 1 (Mar. 1974), pp. 27-31

It has been well documented that many species of fireflies use their flash for courtship. Each species employs a precisely timed set of flashes to attract a response only by a potential mate of the same species.

The flash communication of Photuris fireflies, however, is not well understood, predominantly for two reasons. First, successful courtship in Photuris fireflies has rarely been observed. Second, many female Photuris are mimics—attracting and preying on the males of other firefly species by imitating the flash of a responding female. This leads to the question: Do female Photuris use their own courtship flash to attract prey?

Photuris fairchildi is the only Photuris species occurring in Nova Scotia, Canada, and is common in moist areas. Many flashing males were observed for this study, but only two of these achieved successful matings.

Courtship Flashing

The flash pattern of the male P. fairchildi varies from one to six flashes, repeating the pattern approximately every 2.5 seconds. Interested females respond with a single flash about 1.5 seconds apart.

In the first successful mating observed, a male emitted a double flash, with the second flash dimmer than the first. The female responded with a single flash with a 1.5-second delay. The male landed and emitted a 3-pulsed, then a 4-pulsed flash. Simultaneously, the female increased the number of her flashes. Each increased their number of flashes until both were flashing continuously. They met under a leaf, stopped flashing, and mated.

The second observed mating occurred in an area where most males emitted 3- or 4-pulsed flashes. A female responded to one male with her single flash. Both the male and female then began to flash continuously. The male landed next to the female and mating began.

Aggressive Mimicry

Female P. fairchildi are mimics and prey upon other species of fireflies. They have been observed feeding on Pyractomena linearis and Pyractomena borealis. Pyr. linearis females have a 1.5-second delay in responding to their male while Pyr. borealis females have a 1-second delay. In mimicking female Pyractomena, P. fairchildi responded to both male Pyractomena fireflies and flashlight signals imitating male Pyractomena with a single flash of 1.5-second delay—the same flash as their courtship signal.

Occasionally a female P. fairchildi would respond to a male P. fairchildi with a single flash but did not increase the flash number as courtship progressed. The male would hover, repeat his flash several times, then fly away.

Discussion

Female P. fairchildi are aggressive mimics who use a single flash with a 1.5-second delay to lure in male Pyractomena. But the same single flash with a 1.5-second delay also serves as their courtship response to the male of their species. However, the male will not land and approach her if her response remains a single flash—she must instead increase the number of flashes as the male approaches. The male’s behavior suggests that they are not attracted to aggressive females, who may be looking for a meal instead of a mate.

Whether female Photuris fireflies ever lure in and feed on male Photuris fireflies in the wild has not been established, although firefly researcher Dr. James Lloyd reported that he once observed a female feeding on a male Photuris.


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