April 29th, 2006
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.