A firefly that doesn't light up, Ellychnia corrusca

Winter Firefly (Ellychnia corrusca) hiding in the bark of a
maple tree.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

As I catalogue each species of animal that I find living in my yard, I include quick facts about each animal. Things like: Where does it go in the winter? For one entry, the banded net-wing, I told you that it hides in crevices in the bark of trees during the winter. Given this bit of information, and the fact that I hear woodpeckers digging bugs out of trees every morning around my yard, I thought it might be interesting to look under the bark of a maple tree to see what I might find.
Within seconds, I spotted three specimens of an insect that bears some similarity to the banded net-wing, but which had quite different coloration. Having grown-up in New England chasing bugs very much like these, I had a suspicion about what they were. If I hadn't known, then I would have been able to start with the similarity to the banded net-wing and work backward through taxonomy using the handy tools at bugguide.net to identify it.
How to identify insect species

This is the same Ellychnia corrusca in the above and below
photos, but with it's head clearly extending beyond the
pronotum, which goes counter to species descriptions.
The other photos all show the head tucked and hidden,
so it seems that position is preferred, but a matter of
behavior rather than basic body architecture.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

Starting from the banded net-wing page, we can click on the taxonomy links at the top of the entry. First, we click the Genus Calopteron and scan the pics. They all appear to be bicolored with a different wing-shape than the specimens I found today. Continuing back, we don't see anything close in appearance to our specimens until we get to the Superfamily Elateroidea which is comprised of click beetles, fireflies, and soldier beetles.
Even then, I don't see a picture that closely matches what I've found, but there is enough diversity here that it might be included and I don't want to have to go further up the chain into much broader beetle categories until I have exhausted possible candidates at the Family level. Within the Superfamily Elateroidea, there are twelve Families. I can immediately rule out click-beetles which tend to have a hard, chitinous outer wing cover (elytra). I can rule out borers and Texas beetles.

From there, it's a process of elimination. I choose one family, enter it into the search box at the top of the page and look for a close match to what I've found. I started with Lampyridae (Fireflies) and quickly found that the images of various species in this group look very much like our mystery bug. From there, we have another process of elimination. There are a handful of subfamilies, and then tribes within the subfamilies, but clicking on an image that looks almost exactly like our subject, I find the species Ellychnia corrusca. Ellychnia corrusca is sometimes commonly called the winter firefly.

The body length of 14mm is the surest clue to the exact
species once it's been narrowed down to the Genus
Ellychnia.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

That gives me a strawman that I then try to rule out.

• Size of my specimen: 14mm, reported size of Ellychnia corrusca 10-14mm. Check. 
• Complete lack of bioluminescent organs at tip of abdomen? Check.
• Pronotum shape and markings, check.
• Elytra details, check. 
• Antenna segment details? check.
• Range? Northeast United States, check.
• Habitat? check.
• Behavior: overwinters as adults in tree bark? Check.
• Behavior: adults known to feed on maple sap in early spring? These specimens were found on a maple tree on March 15th, check.
• Head hidden by pronotum when viewed from above? Uh-oh. No. In an ID photo I took, the head is clearly visible from above. Let's dig deeper.

I search the web for other photos and descriptions (from reputable sources) of Ellychnia corrusca and find some showing the head visible as in my photo. I then go back out to the tree where I found this insect and look for others. They have their heads "tucked" under the pronotum.

In reviewing the photos I took of the original specimen in situ, I see it similarly posed, with head tucked and not visible from above. Apparently, this identification key listed by bugguide.net refers to certain postures and is not absolute for this species.

Ellychnia corrusca with pronotum angled down and head
hidden from view from above as in most species accounts.
This is the same specimen as in the photo to the above-right.
Photo by Brad Sylvester. Copyright 2012. Do not copy.

When I can't rule out Ellychnia corrusca, I see if I can rule in any other species. Every resource I can find tells me that although there are three known species of non-luminescent lightning bugs in New England. Only one is larger than 7.5 millimeters in length, which rules out all the others as this is clearly a lightning bug. So there we have it. Ellychnia corrusca, a lightning bug or firefly that doesn't ever light up and is active in the daytime instead of the night.

Undiscovered new sub-species?

What's particularly interesting is that the University of Alberta suggests that the insects currently identified as Ellychnia corrusca as "possibly consisting of several species, but not sufficiently studied or understood to differentiate between them." This is based on observed differences between specimens identified in different regions of their accepted range.

UA suggestion is correct) currently classified as Ellychnia corrusca. Thesis material, anyone?

Given the tremendous complexity of the wild forest biosphere, I've often thought that there are surely species of plants and animals (particularly arthropods), even in well settled areas like my own backyard, that have not yet been discovered or identified. Do the various sub-species of Ellychnia corrusca qualify? Because the differences may occur geographically, it's unlikely that I would be able to find more than one of the proposed sub-species (if such exist) in my yard, nevertheless, I will keep a specimen preserved and compare it against future finds to look for inconsistencies. I will certainly never look at a lightning bug in my yard the same way again knowing it might be an unrecognized sub-species!

Quick facts about the Ellychnia corrusca:

Lifespan of the winter firefly: about one year

Life Cycle: Ellychnia corrusca, according to the University of Alberta's E.H. Strickland Entomology Museum, spends the winter in the crevices of tree bark, moving very little and never leaving the tree until March. In March, it begins flying again. mating season is April and May. The adults die in late spring, sometimes prematurely by drowning in the sap collection buckets of those tapping maple trees. The larvae of Ellychnia corrusca, says the E.H. Strickland Entomology Museum, live in rotting wood and are predators, likely eating grubs and slugs that are also found in or on rotting wood.

Diet: Adults live on plant liquids such as maple sap, maple flower nectar, and possibly fluids from flowers during the fall before they find a winter hiding place, according to the E.H. Strickland Museum.

Range: Bugguide.net credits researchers Downie and Arnett with stating that the winter firefly lives in the eastern United States, from Maine to Wisconsin and as far south as Maryland. Populations are also found on the western coast of the Untied states into Colorado and Arizona. In Canada they are found in the east and in British Columbia.

Where does it go in winter? The winter firefly stays hidden in the folds of tree bark in the winter, although it may move a few inches from one place to another, it otherwise stays put during the cold months.

Notes: Most people think that all lightning bugs or fireflies light up and come out at night, but Ellychnia corrusca does not possess bio-luminescent organs and is diurnal. Most (if not all) northern, luminescent fireflies overwinter in larval form inside rotting wood. Ellychnia corrusca, however, pupates before the winter snow and overwinters in adult form.

Ellychnia corrusca taxonomy:

Kingdom: Animalia (Animals)
Phylum: Arthropoda (Arthropods)
Class: Insecta (Insects)
Order: Coleoptera (Beetles)
          Suborder: Polyphaga (Water beetles, Rove beetles, Longhorn beetles, Leaf beetles, 
          Snout beetles, and Scarabs)
Superfamily: Elateroidea (Click beetles, fireflies, and Soldier beetles)
          Family: Lampyridae (Fireflies)
                    Subfamily: Lampyrinae
                             Tribe: Photinini
Genus: Ellychnia
Species: Ellychnia corrusca