Swarms of Mosquitoes Are Probably Harmless Midges

By Chris Williams on June 1, 2016.

At this time of year, we often get calls from panicked citizens who are seeing huge swarms of mosquitoes hovering in their yards. We can usually reassure them by explaining that what they are seeing are chironomid midges. These flies are also known as “nuisance midges,” to distinguish them from other smaller midges that bite. These don’t.

Nuisance midges come in a range of sizes but some of them do look a lot like mosquitoes. They are similar in size and shape and will even make that buzzing sound in your ear like mosquitoes. If you could look at them under magnification though you would see that they do not have the piercing proboscis to suck blood, they don’t have scales on their wings like mosquitoes, and the male midges have very bushy antennae (see Mosquitoes or Midges?).

These midges become nuisances at various times during spring and summer when they emerge from their watery habitat in large hatches or swarms. They often emerge around sundown and may fly to bright lights or light-colored walls. During the day, you can see thousands of midges hovering in a shaft of sunlight, alarming those who mistake them for mosquitoes. Any one species of midge can have several different hatches spread over a couple of weeks. While the hatches may go on for an extended time, each individual midge only lives long enough to mate and start the next generation.

Water-front Living Means Living With Midges

Midges cause the biggest problems for waterfront residents or those in lakefront communities. Besides being a nuisance in large numbers, midges also leave messy fecal droppings on boats and other surfaces. They tend to rest on walls during the day.

Midge management is difficult because in severe cases it must almost always be accomplished (if it’s possible at all) on a community-wide basis. Worm-like midge larvae develop in aquatic sites like lakes, streams, ponds, drainage ditches. The larvae feed on algae, but they themselves are important food for fish and other aquatic animals which is why their control is controversial and difficult.

Light Management Can Make a Difference

There are a number of measures that can be used on a community basis to help reduce midge problems, not all are effective. In some cases, the body of water can be treated with an insect growth regulator. A small body of water can be stocked with fish to eat the larvae. On an individual basis, the most important thing you can do is to reduce, relocate, or eliminate bright outdoor lighting that is drawing midges to your home or dock (see Porch Lights Attracting Bugs? Choose a Better Bulb). Bug “zapper” light traps are not an effective way to reduce midge numbers either (see Bug Zappers Give No Relief From Midge Swarms).  Some people plant trees or use walls or other tall barriers to block light between the aquatic breeding site and their home.

Chironomid midges are a seasonal nuisance, but are also beneficial insects since both the larvae and the adults0 provide food for fish, birds, and other animals. Unfortunately, midges can’t be totally eliminated and are one of the trade-offs of living near the water. Just be glad they don’t bite or carry diseases like mosquitoes!

Photo Credit : “Chironomus plumosus – male (2007-06-08)” | Wikimedia Commons.



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