Question

We recently moved into a new home right on the shore of a large lake. When we try to use our deck, we are plagued by swarms of small flies that the locals call midges. Sometimes it seems like there are hundreds of them sitting on the side of the house. Would it help if we got one of those bug zapper traps to use around our deck?

Answer

Unfortunately, midges are something you have to put up with when you’re fortunate enough to live near the water. On the plus side, although midges look a lot like mosquitoes and even make a buzzing sound like mosquitoes, they don’t bite. These nuisance midges (also called chironomids) are different than the smaller biting gnats that are sometimes called biting midges.

Midges are attracted to lights and light-colored walls so outdoor light traps or “bug zappers” do catch a large quantity of midges (which most people mistake for mosquitoes), but using a light trap outside during a midge hatch is kind of like using a dipper to try to empty the ocean! Zappers may also attract midges into the area.

The wormlike midge larvae live in lakes, streams, ponds, drainage ditches, creeks…in clean or polluted water. Most feed on algae, and are in turn fed upon by fish and other aquatic animals. When they’ve completed their development, the adult midges emerge from the water. They tend to emerge all at once in large swarms or hatches of thousands, and they often travel together in small clouds. The swarm serves as a kind of “singles bar” for male and female midges looking for mates.

The largest swarms of midges emerge around sundown on warm, quiet evenings, but smaller swarms can occur throughout the day. Swarms last for minutes or hours. Different hatches usually appear over a period of several days but each individual midge only lives for a few days. During the day, swarms of midges congregate in cool, shady spots, staining building walls with their droppings.

Trying to control midges with pesticides can be tricky. Spraying yards for adult midges suppresses the midges only temporarily because new swarms are emerging all the time. Controlling the larval midges in their water environment is sometimes possible but products used can also harm fish and other aquatic organisms. Also, eliminating midge larvae affects other animals in the food chain that rely on those larvae for food. Treating a large body of water like your lake usually requires coordination and permission from other state or local agencies.

But you don’t have to just throw up your hands in defeat. While you can’t change the big picture or the midges’ environment, there are some things you can do to make your home a little less attractive to midge swarms.

• Avoid using bright lights around docks, doorways, pools, patios, and areas where people gather.
• Direct lights to shine only where needed or shield the beams. Don’t shine bright lights on light-colored walls.
• Use lower wattage bulbs and substitute sodium vapor lights or dichrom yellow bulbs in outdoor lights.
• Set yard and pool lights to turn on one hour after sunset to avoid the period of greatest midge activity.
• Close inside curtains or blinds at night to keep from attracting midges to lights at windows and doorways.
• Midges don’t like to fly in wind, so using fans on your deck will help keep them away.