Looking for Snow Midges at Nugget Falls | Bob Armstrong's Nature Alaska

Looking for Snow Midges at Nugget Falls shows Diamesa midges as adults and larvae.
A stream flowing from beneath a glacier is a very inhospitable place for life. Compared to others, glacier-fed streams are very fast, very muddy, and very cold. Like the water, some portion of the streambed is in constant motion as boulders, cobbles, and gravels shift and roll downstream. The places were life might live – on the surfaces of rocks and the spaces between them – are unstable and unpredictable. Despite the harsh nature of a glacial stream, a few well-adapted species not only survive, but thrive in these conditions. One of them is an insect, a nonbiting midge called Diamesa.
Diamesa are true flies. Females lay eggs on wet rocks at the edge of the stream. Larvae hatch from eggs as elongate, worm-like creatures with hard heads and soft bodies. Lacking true legs, they cling to rocks using short appendages equipped with hooks.
Larvae transform into pupae and the pupae transform into adult flies that somewhat resemble mosquitos.
Diamesa is often the first animal to colonize streams exposed by retreating glaciers. • The glacier-fed streams where they live may only reach 36 F by late summer.
Near glaciers Diamesa feed mainly on a thin film of microbes scraped from the surfaces of rocks.
Diamesa is often the sole inhabitant of the upper reaches of glacial streams.
Larvae have unusually long appendages which help them cling to rocks in high-velocity water
As glaciers melt and retreat, streams get clearer, warmer, and more stable allowing other insects to outcompete and replace Diamesa.
By shedding water and producing sugars for antifreeze, larvae can survive winter frozen in ice
While most adult midges have wings and take part in mating swarms, some adult Diamesa have reduced wings or no wings at all.
Some Diamesa emerge from streams as adults in mid-winter; mating may take place under shelf ice or shoreline rocks
Adults can be seen walking on glaciers at temperature down to 3 F. When held in a warm hand, these adults will quickly die.