What’s With All These Flies?

The tiny fly-like creatures one sees swarming by the zillions now, appearing like columns of smoke, are midges, very likely in the “Chironomid” genus, thankfully one of the non-biting midge species. Many different species of midges are widely distributed throughout the world, some being terrible

biting pests. The large swarms of midges we see every spring about this time in Door County, more pronounced near water, are from eggs laid in the water last fall. The larval stage under water became dormant during winter. Now the life cycle is being completed with the emerging from the water by the adults – whose life span is only 3-5 days. The higher the nutrient content is of the water the greater numbers of midges result. Use of especially lawn fertilizers and its run-off into lakes, ponds and streams

contributes to the nutrient-rich water and, as a result, all the more midges.

One of the benefits of midges is that quite a few wild creatures eat the adults, creatures including the nymphs and adult dragonflies, predacious diving beetles, many species of fish, and small migrating birds now arriving in Door County, some to nest here, others only resting and feeding before

heading northward. Each May we associate the exciting and challenging “invasion” of warblers with the hatch of the midges. Much of the warblers’ food consists of the tiny midges.

There will be several more complete life cycles of these midges during the summer, each lasting from 2-7 weeks, from egg to adult. These life cycles are not nearly as large and as noticeable as the spring emergence of the midge adults going on right now. By the way, these midges are greatly different from the much larger so-called lake flies which can emerge from the water a little later. Some of our largest hatches of lake flies in Door County have occurred in June. Large hatches of lake flies reflect high quality of the bodies of water from which they emerged.