A firefly without a light

 

This little apple tree has been a magnet for many kinds of beetles, butterflies, and wasps. Not so much for the flowers but for sap oozing wounds and the ripe apples. The narrow, flat, dark-colored beetles feeding on overripe apples are fireflies known as Diurnal Fireflies (Ellychnia corrusca). Unlike other fireflies the Diurnal Firefly does not possess bioluminescent organs and is active by day than night. Another name this firefly goes by is “Snow Firefly” because they are sometimes active on warm winter days. The genus name Ellychnia is from the Greek and means “a lamp-wick.”

Description
Body shape is oblong to oval, 10-14 mm long, and overall body color is black. The half-moon shaped thorax central disk and margins are black, the area between red or reddish-yellow. The wing cover (elytra) surface is dark brown to black, finely granulate and covered in a fine, flattened yellowish pubescence. Along the edges of the abdomen are small pinkish markings where the larva’s light organs used to be.

The larvae are black with pinkish light producing organs on the edges of the abdominal segments. In overall appearance they look like some sort of dark black flattened millipede but the presence of three pairs and not many pairs of legs will quickly identify them as insects. The body is narrow and the body long with shingle-like segments.

Taxonomy
Class: Insecta (Insects)
Order: Coleoptera (Beetles)
Suborder: Polyphaga (Rove, Scarab, Lady Beetles, Weevils)
Superfamily Elateroidea: (Click, Firefly and Soldier Beetles)
Family: Lampyridae (Fireflies)
Subfamily: Lampyrinae
Tribe: Photinini
Genus/species: Ellychnia corrusca

Life Cycle
Diurnal Fireflies hibernate as adults and emerge in April to mate. Larva hatch from eggs laid in woody debris. The larvae are carnivorous feeding on grubs and other small invertebrates and possibly slugs which they find in soft, rotting wood. Unlike the adults, the larvae can flash light from specialized organs on the abdominal segments of their bodies. Adults lose this ability shortly after emerging from pupation.

Adult Diurnal Fireflies feed on nectar, tree sap, and juices from ripe fruits. They pass the winter under loose bark of trees but will come out on very warm days and feed on sap dripping from tree wounds.

Habitat
Adults can be found in moist fields and coniferous and deciduous forests. The larvae live in soft decaying wood where they prey upon small invertebrates.

Range
Diurnal Fireflies occur over most of eastern North America to British Columbia and at higher elevations in the western mountains of the US.

References consulted
Blatchley, W. S. (1910). The Coleoptera or Beetles of Indiana. Bulletin 1, Indiana Department of Geology and Natural Resources.

Bug Guide (Genus Ellychnia – Diurnal Fireflies)

Luk, S. P. L.; Marshall, S. A.; and Branham, M. A. (2011). The Fireflies of Ontario (Coleoptera: Lampyridae). Canadian Journal of Arthropod Identification No. 16:1-105.

Majka, C. J. (2012). The Lampyridae (Coleoptera) of Atlantic Canada. Journal of the Acadian Entomological Society 8:11-29.

Rooney, J. A. and Lewis, S. M. (2000). Notes on the Life History and Mating Behavior of Ellychnia corrusca (Coloeptera: Lampyridae).

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