The Gallery of
Photinus pyralis

A collection of microphotographs presented by Terry Lynch
Naturalist, Photographer, Journalist

The firefly man

I've been studying fireflies so long that I've turned green and glow in the dark :-) at least it would seem so from this photo enhanced self portrait. I'm holding a jar of Photinus pyralis fireflies, some of the first males to emerge from their subterranean pupae. Below you will find additional microphotographs of Photinus pyralis which illustrate various aspects of their life cycle. If you wish to use any of these photographs please write to me and ask permission. Also be sure to give me appropriate credit and link to or list this site. Thanks!

Photinus pyralis orgy

Photinus pyralis males can be found during the early summer in the southeastern United States where the males fly about during twilight searching for females. The males of P. pyralis are highly competitive and even after one male has copulated with a large female, other males will attempt to copulate, often with each other. Very likely the males are aroused by chemicals released by the females as when a female has been places in contact with a moist paper towel, and that paper towel is set inside a jar with males, the males can be stimulated to flash their lanterns much early than usual, even when the female is not present.

The compound eye of Photinus pyralis consists of hundreds of hexagonal lenses covering a spherical surface. When the male firefly flashes, it then hovers and awaits a female flash response which occurs about two seconds later. Seeing the female's flash, the male orients toward the female, flying toward her. Then the male flashes again and awaits another response from the female. This processes is repeated until the male is able to locate and land upon or near the female which is usually perched upon a leaf, plant stem, the trunk of a tree or other vegetation close to the ground. Then the male and female copulate with each other and may remain copulated late into the evening. The male's large spherical compound eyes certainly enable it to more rapidly locate a female than would occur if fireflies had smaller eyes, as then more flashes would be required before a male could home in upon a female. Two large compound eyes enables more precise orientation than would be possible with two small eyes. Because the compound eyes are spherical, only a few of the hexagonal lenses in this photomicrograph taken at 28X are in focus. Really what one is seeing here is a sharply curved surface of hexagonal lenses which quickly become blurred as one approaches the outer edges of the photograph and the lens of the compound eye curves around to attach to the firefly's body.

Photinus pyralis eggs in cluster

Eggs of Photinus pyralis are bioluminescent. This can be observed by collecting eggs and placing them in a Petri dish in a darkened room or closet. Let the eggs set undisturbed for 24 hours. Then enter the darkened room and let your eyes adjust to the dark for about 5 minutes. Then gently tap the Petri dish to cause vibrations. The eggs should glow. This is rather spectacular if done several days before larvae are due to hatch as each larvae inside the eggs have tiny lanterns which will light up. This photograph of a cluster of eggs was photoenhanced to simulate how eggs of P. pyralis appear when they glow. The photographer has actually collected and observed large numbers of firefly eggs glowing, but this is a challenge to photograph given the low sensitivity of film or digital cameras.

Photinus pyralis egg and embryo

Eggs of Photinus pyralis are deposited by females in the upper layer of the soil, under leaves and among decaying vegetation. Females will readily lay eggs in captivity and the eggs can be incubated to yield tiny firefly larvae.

Photinus pyralis egg with larva almost fully developed

Here is seen a P. pyralis larvae almost fully develop inside its egg case. Larvae hatch from eggs in about 12-14 days.

Photinus pyralis egg

The segments of a P. pyralis larva are clearly visible in this microphotograph. Also, larva can be observed to glow inside eggs when disturbed by making a sharp vibration or gently knocking the container in which the eggs are incubated.

Photinus pyralis egg with embryonic larva showing mandibles

This microphotograph clearly shows a P. pyralis larvae with mandibles fully developed and beginning to take upon coloration.

Photinus pyralis I-instar larva newly emerged from egg

Photinus pyralis is almost translucent when it first emerges from its egg case. This affords an excellent opportunity to photograph the young larvae and observe internal structures.

Photinus pyralis I-instar larva

After emerging from eggs, P. pyralis larvae begin to tan. As this microphotographs shows, the I-instar larva has a very complicated head and mouth parts, with deep red eyes which probably enable it to aggregate with other larvae.

Photinus pyralis I-instar larva eating earthworm

Here a I-instar P. pyralis larva has attached itself to a section of earthworm and is feeding upon the earthworm.

Photinus pyralis I-instar in aggregate

After hatching from eggs Photinus pyralis larvae will collect together or aggregate. This enhanced image gives an impression of the glowing of larvae to show how bioluminescence may play a role in aggregation a behavior which also may be influenced by tactile stimuli, taste or smell, given P. pyralis larvae certainly have these senses which they may also use to identify their food of choice, earthworms.

When observed with the naked eye, one is able to see two tiny lanterns which glow brightly at the posterior end of the larvae; this enhancement does not actually show larvae glowing, but gives an impression of how such light might appear when diffused through the larvae's body. How other P. pyralis larvae perceive one another is, of course, also a matter of speculation which requires a bit of imagination upon the part of humans. One may speculate with reasonable certainty that such perception involves not only vision but all the senses of the young firefly larvae.

When a 5 cm. long red earthworm was placed in a one-half pint jar containing newly hatched P. pyralis larvae, the earthworm had succumb to their highly toxic venom within two hours, permitting the larvae to feast upon the earthworm's flesh, dissolving and drinking it, a behavior which the author has observed and video taped. (See Early Instar Gallery)

Additional Photos Coming Soon!

If you are anxiously awaiting the arrival of more photographs, please be patient. Additional photos will be presented over time as interesting specimens are prepared and photographed. Please click on the links below to view additional photomicrographs and special natural history pages presented for your education, enlightenment and enjoyment. Thank you!

The Urban Jungle

Cicada Hieroglyph

Dance de Nematodes

Pine Tree Inflorescence

Springtails Gallery

Presenting Anurida granaria; a bioluminescent Springtail

Firefly Mysteries

Blinks and Links

The Amateur Naturalist

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