Big dipper firefly (Photinus pyralis) mating frenzy

Male big dipper firefly attempts to mate with coupled pair (July 8, 2011, Urbana, IL). Click image to magnify.

We’ve experienced the nightly show of millions of fireflies in our yard and the surrounding fields over the past month. The numbers appear to be reaching its seasonal peak.

Mating pairs are swarmed by males eagerly in search of females. The males will couple with any part of the mating pair in their pheromone-induced mating frenzy.

A unique mating deception (described at Six Months Ago: An Abundance of Fireflies) occurs in this species.

Big dipper fireflies get their name from the dipping flight of the males as they flash, advertising their availability. The light is brightest as they dip and fades as they ascend.

Larvae of this species feed on earthworm.

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Six Months Ago: An Abundance of Fireflies

Big dipper firefly (Photinis pyralis) emerging from vegetation as the rains subside.

Regular mid-June rains were followed by an abundance of fireflies. I find myself longing for the warm weather and its accompanying lack of snows and wind chills.

Photuris females sometimes mimic the flash patterns of female Photinus fireflies, attracting Photinus males who are promptly eaten. The Photuris females sequester the Photinus males’ defensive chemicals in their own tissues and use the Photinus males’ nutrients to nourish their developing eggs.

Once sated, the Photuris females will flash their own species-specific pattern, attracting mates of their own species.

Photuris sp. individual feeding between bouts of rain.

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Deceit Among Fireflies

Male Photuris sp., June 17, 2010, Urbana, IL.

Photuris is the second most common genus of fireflies in the U.S. The males flash green or yellow-green. Photuris females sometimes mimic the flash of the neighboring Photinus females, attract flying male Photinus fireflies, and then capture and devour them.

The female Photuris fireflies accumulate defensive steroids from the Photinus males, as well as nutrients for the development of their developing eggs. Once the eggs are mature and the Photuris female is ready to mate, she changes to her own species-specific flash pattern to attract to attract males of her species.

Male Photinus firefly preparing for flight. He does look delicious, doesn't he?

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Firefly Larva

Lampyrid Larva

While moving some concrete blocks I encountered the firefly larva shown above. The larvae are carnivorous, feeding on other larvae, terrestrial snails, and slugs. The camera certainly does a nice job of capturing the pinkish tinge that is maintained through adulthood (see below). Double click the picture of the adult to better see its mouthparts.

Adult Lampyrid (Photo taken 7/2009, Urbana, IL, USA)

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