Tuesday, August 5, 2008

Meeting pruinescence head on.

From Wikipedia: Pruinescence, or pruinosity, is a "bloom" caused by pigment on top of an insect's cuticle that covers up the underlying coloration, giving a dusty or frosted appearance.

Pruinescence occurs in many odonates (damselflies and dragonflies). Within the dragonflies it is commonly found in the skimmers (Libellulidae). Typically, only males pruinesce. At least two pruinescent libellulids are found in BC’s Lower Mainland. (Noun, verb & adjective, all in one paragraph.)

Head-on pruinescence: Western Pondhawk, Erythemis collocata, near Chilliwack, BC.

The Western Pondhawk lives around ponds and marshy lakes. The abdomens of females and pre-pruinescent males are green with a dark mid-dorsal stripe. Males eventually turn dusty blue. The generic name, Erythemis, means “the red one.” This is not intentional contrariness; southern species, for which the genus was originally named, turn red.


The Common Whitetail, Libellula lydia. Richmond, BC.

The Common Whitetail is a dragonfly of muddy pond edges and other small, quiet patches of water. Females have a golden-brown abdomen. Pruinescent males are white-bodied.

Mature males aggressively defend their territories, alternating between perching on choice landmarks and brief attack-flights at rivals. It is likely that pruinescence acts as a visual territorial threat. It may also help reflect sunlight, useful in a small creature perching at length in the open.

2 comments:

membracid said...

I did not know this! Thanks for the informative post. I love learning new words :)

Hugh said...

I didn't know this either. The word popped up in the book I was using to identify the species. It is no doubt a rarely used word, so I used it numerous times, just to give it a boost.