Blackflies - at Trail Wood

Trail Wood #70 Earl Plato
Edwin Teale watched the mid-April life cycle of the blackflies at Trail Wood.
“ again and again I return to watch these
Simuliidae, the black flies, through the window of the clearer water. They are found only in the swifter current where the white water of the cascades provide them with extra oxygen they need. Hour after they wave back and forth sweeping two fanlike organs through the water straining out infinitesimal bits of food mainly algae and diatoms on which they feed. Peering down I observe them in the time of their larval life and spin their boot-shaped underwater cocoons open at the downstream end, I have never been fortunate enough to observe, Like the larva, the pupa breathes through the tracheal gills. At this stage in the life of he blackfly, the rocks of the rapids are carpeted with hundreds of cocoons. Within each as the transformation into the adult nears completion, a bubble forms. Then the cocoon splits and the blackfly, riding within the bubble shoots upward through the tumbling water, pops to the surface amid flying spray and instantaneously lifts into the air on its tiny wings. …”
Writer’s note: I saw this phenomena of black flies emerging from the fast flowing current of Whiskey Rapids in Algonquin Park. Thanks to the park ranger who told me where to go.