As written previously, we are beginning work on an educational video about Lake Ontario ( there is information on my author website at www.susanpgateley.com on this).
Part of the video will consist of information on how the lake impacts the seasonal shoreline ecology, regional history and present day economic activity. Recently I've been chasing midges with the camera.
Each spring one component of the Lake Ontario food chain makes itself known to all who live within a half mile or so of the south shore. Around the third week of April the first big aquatic midge emergences occur. Like magic, wooded and brushy areas of the nearshore area fill with swarms of dancing mosquito sized insects. Sometimes small swarms gather into vast aggregations that look like plumes of smoke hanging over trees.
During a big hatch I see spring migrant birds feeding on the insects, picking them off leaves as phoebes and swallows dash through the swarms. And every spiderweb in the woodlot fills with midges.
Where do they come from? And why are they here?
These aggregations of harmless non biting flies, many of them of the family Chironomidae, are a vital part of both aquatic and terrestrial food webs. The larval stages live on the bottom or on aquatic vegetation in lakes and ponds. Fish of many types including minnows, trout, sculpins, and juvenile Great Lakes sturgeon feed on them. Along the shore adult midges are a food source to spring migrant birds who pause along the forested areas of the Great Lakes to rest and feed before heading north.
The numbers of these insects are simply unimaginable. Some live on the bottom hundreds of feet down as aquatic larvae feeding on detritus and bacteria in the black depths of the lake. Some live near shore in the sunlit shallows. They are world wide in distribution. Wikipedia says they are called 'lake flies' and muffleheads. Some feed on nectar or pollen. Some don't feed at all.
The swarms are formed by male midges. They apparently use sound to find one another and organize into a swarm. and the male midges' feathery antenna are designed to pick up the high frequency noise of their millions of beating wings. One Internet article says it takes ten midges to form a self organized swarm. Then the females fly through and pick somebody out for their betrothed. Off they go to make more midges. Somehow she then gets back to the lake to drop her eggs. I would suspect a south wind would be of help around my neighborhood. And somehow they all coordinate these mass emergences.
The Internet says some species use lunar cues to synchronize. If these midget midges of the early spring boatyard are from the lake's shallows, perhaps they use the moon to synchronize their emergence from the water to take flight. Later in the summer we'll see some bigger ones hanging onto the boat's cabin top and sail covers. Some species emerge continuously throughout the summer rather than in one giant event.
The swarms are quite mesmerizing to watch as tens of thousands of midges seem to act as a single entity. Quiet morning and evening hours are the best bet for seeing a really big swarm. Eventually I"ll get some video up on You Tube of them.