June 2015 Featured Paper

Late-season Patrolling Behavior and Flash Patterns of Female Photuris lucicrescens

Christopher M. Heckscher
Northeastern Naturalist, Vol. 21, No. 1 (2014), pp. 72-74

Read the original paper. (Subscription to BioOne is required. Check your local library for access.)

Photuris lucicrescens is a firefly that usually breeds in moist flood plains bordering forests. The courtship signal of the male is a long flash that begins dim, but rapidly increases in brightness until brilliant, then ending abruptly. This flash is usually given around low vegetation, sometimes while perched and sometimes while flying in a zigzag pattern.

During his studies of this firefly in the mid-Atlantic and northeastern states, the author noted unusual flash behavior occurring in the latter part of the season. At the beginning of the season, from June 16 to July 2, individuals emitted the long courtship flash. Later in the season, from July 2 to August 10, only single or multiple flashes were observed— no long courtship flashes. In this late season period, no males were observed; these flashes were all given by females. Furthermore, these females were observed in the forest, not in their typical flood plain breeding areas.

So what does this unusual flash behavior signify?

Some female Photuris fireflies are known to prey on male Photinus fireflies to acquire the defensive steroid chemicals in their blood that afford protection from predators. The Photuris female does this by mimicking the mating flash of the female Photinus, capturing the male when he responds to this signal. Female P. lucicrescens are large fireflies and can be assumed to be one of these predatory Photuris fireflies. Unlike most predatory Photuris, however, P. lucicrescens was not observed imitating a perched Photinus female, but rather seen to emit single or multiple flashes while in flight. These flashes resemble the male courtship flashes of several species of Photinus fireflies occurring in the same region.

The author hypothesizes that after mating has occurred, the female P. lucicrescens becomes predatory, but preys on Photinus females rather than males. Imitating a male Photinus in flight causes a female Photinus to respond with a flash, thus revealing her position to these hunting Photuris females.

Both male and female Photinus fireflies contain the defensive steroids that afford them protection from predators. The female Photuris could just as likely gain the same chemical protection by feeding on a female Photinus as from consuming a male.

Further field studies will be needed to determine if this hypothesis is correct. Observation of a P. lucicrescens attacking a female Photinus in this way has yet to be recorded.

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