diurnal fireflies

For the past few weeks, I’ve been seeing quite a few Diurnal Fireflies, also known as Winter Fireflies, while making my “insect rounds” here at the farm. These beetles (for all fireflies are actually beetles) have dark brown elytra and an orange-marked pronotum, as in the above photo. Most commonly, I find them moving slowly along the deeper grooves in the bark of hardwood trees, but I also found a couple of active individuals moving about on the snow surface on a mild day in January. In this region, they may be found in good numbers in April and May, and once again in September and October. However, once you get used to spotting them, you’ll also find them on fall-flowering plants as well.

When I first discovered these fireflies, I thought that they must be the regular fireflies which put on pyrotechnic displays on summer nights. I even collected a few to bring indoors for the night to see if they would produce even a weak flash. No such luck. After comparing them to nocturnally active members of the firefly family Lampyridae, I realized that they looked much the same, but seemed to lack light organs in their abdomen. I’ve posted a couple of photos below which show the non-luminous Diurnal firefly (top), and a pair of mating luminous fireflies (not sure which species) below — note the white abdominal sections on the luminous pair, which would be the parts that flash if you were to see them at night.

Of the sources I’ve read, it seems that all of the Diurnal fireflies in eastern North America belong to a species complex referred to as Ellychnia corrusca. Apparently, there hasn’t been a great deal of work done on Ellychnia, but it probably consists of several species. Their larvae resemble those of the other species and are also said to glow. Even newly emerged adults are said to have a weak glow for the first few days after they eclose.

Each year, I try to spend quite a bit of time photographing luminous members of the Lampyridae family when they become active in midsummer. I’ll try to post some follow-ups on my observations of the nocturnally active members of this interesting insect family.

Additional references on Ellychnia corrusca:

See “Winter Fireflies” on page 12 of the .pdf newsletter, Fireflyer Companion, Vol. 1, Number 1, Winter 1993-1994.

A webpage on Ellychnia corrusca from the University of Alberta’s E. H. Strickland Entomological Museum online collection.

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7 Responses to “diurnal fireflies”

  1. Aydin Says:

    Are these “fireflies” that don’t have light organs in the Lampyridae?

  2. burning silo Says:

    Aydin – Yes, Ellychnia are members of the family Lampyridae. From what I’ve read about them, the larvae look the same as those of other Lampyridae – certainly the ones I’ve photographed which I believe were larvae of Ellychnia. Apparently, the larvae glow, but I haven’t collected any as yet to see if that is the case. That’s one of my small projects for this year. Btw, here’s the classification for Ellychnia from BugGuide.net. Incidentally, this afternoon, while reading about Fireflies, I was a bit surprised to read that some species of Click Beetles also have light organs and produce a glow. Fireflies and Click Beetles all belong to the Superfamily Elateroidea so I guess it makes sense that some species might glow.

  3. Wayne Says:

    Thanks for an illuminating and well-photographed story, Bev. It always brightens my day when brings to light something that I was so in the dark about that I hadn’t even thought about it.

    This strikes me as a fascinating evolutionary phenomenon. I did a little googling and found this abstract of some work that adds to the conversation.

    The photic ability in those members of the family that do it are for sexual signaling and pheromone signally is reduced. In those members that don’t do photic signalling, the pheromone system is strong.

    The photic system is complex, requiring not just the appropriate organs and physiological control, but also the synthesis of luciferin and its deposition – not to mention the large amounts of ATP that are required. I wonder how much of this orchestra the non-photic members have retained? Certainly your photograph shows that there are some gross external changes.

    And then there’s the matter of the glowworms. If both the photic and non-photic adults are able to glow as kids you have to wonder why? The kids aren’t doing sexual stuff and yet they retain what has to be a pretty expensive system. Just what are they down there in the dirt?

  4. burning silo Says:

    Wayne – Very interesting find! Thanks for posting that link. I’ll have to do more follow-up on this topic. The matter of the larvae does seem puzzling. Why would they glow if they don’t really need to, unless there’s some other benefit? I’m wondering if it has to do with protection. I just looked up this reference, as a couple of years ago, I read that fireflies can be toxic to other creatures such as amphibians and reptiles. Apparently, pet Bearded Dragons (a kind of lizard often kept as a pet) have died after consuming fireflies. About the toxins, it says:

    Researchers are uncovering chemicals in fireflies that are related to their luminescence. Some of these chemicals are cardenolides, similar to digitalis. Some are like the bufodienolides found in toads. These flying beetles also contain lucibufagins, a steroidal pyrone. Luciferin, a protein, circulates through the insect’s blood stream, making the entire insect toxic to a wide variety of predators.


    The fireflies’ glow plays a dual role in the life of these beetles. The glow advertises the males’ presence to females during the annual mating dance. But the glow also warns predators of the dangers of eating the beetles. Thus, birds and other potential predators are warned off, or learn the hard way that eating a firefly isn’t a mistake that they can make twice.

    So, that may, in part, explain why the larvae do continue to glow even though it isn’t required for reproduction. Also, it might explain why there is a “weak glow” produced by some of the adult Ellychnia for the first few days after they eclose — perhaps providing them with added protection until they have had a chance to reproduce. From what I’ve read (so far), it seems that fireflies mate shortly after they eclose.

    In any case, there are lots of observations to be made on fireflies. If there’s one thing I’ve read repeatedly when trying to find out more about them, it’s that there is a lot that is still not known about Lampyridae. Of course, that’s true for many insects and spiders, which just adds to the enjoyment of observing them.

  5. Autrice Says:

    There are several of us in the Ohio Valley area wondering where all our fireflies have gone. Our population count is low for this time of year. I was wondering if other people in this area have noticed this, or is it simply a localized phenomenon?

  6. burning silo Says:

    Hello Autrice — We’re just beginning to see the first of our nocturnal fireflies this season (last Friday – June 2nd – was the first night). There did seem to be quite a number out that evening, but not much since due to weather conditions. Last year was a terrific year for them in this area. I think their numbers are very much weather dependent. We’ve had several hot, drought-like summers up here and barely a firefly to be seen. Last year started out dry, but then we had a lot of heavy rains in late spring, followed by some fairly extreme heat. We soon saw huge numbers of fireflies around our farm, and other naturalists in my area were reporting the same. The other thing which they seem to require is the good cover or dense, tall meadow grass and/or a lot of understory vegetation in forests. If you’ve followed my blog at all, you’ll have seen me mention that our yards are all very dense meadow with a mixture of oldfield plants. That seems to provide ideal cover for fireflies. Well, I hope that the Ohio Valley is just experiencing a down-turn in the firefly cycle and that the numbers will soon be up again. Perhaps it’s weather related, although the other issue is habitat destruction – so maybe it’s a bit of both (?). Thanks for stopping by and posting a note to my blog.

  7. Burning Silo » Blog Archive » light up the night! Says:

    […] A few weeks ago, I wrote about diurnal fireflies — members of the Family Lampyridae that do not produce flashes of light at night. They’re still around, but they’re now upstaged by the light show produced by their nocturnal kin. For the next few weeks, the yard will be filled with green glows and streaks of light on occasional evenings when weather conditions are just right. Don noticed the first good showing of fireflies last Friday evening (June 2nd), with dozens of fireflies zooming and arcing above the tall meadow grass around our house and barns. But what is a firefly? Who is the insect behind that neon glow? […]