Gnats Indoors in Winter?

By Chris Williams on January 5, 2017.

Here it is January, it’s frozen outside and we have these tiny flies flitting around inside. I can’t figure out where they could be coming from. Any ideas?  V. B., Everett, MA

The first thing you need to do is have a professional exterminator inspect your home to identify the flies and find the breeding site. Save a few fly specimens for the inspector.

At this time of year, we would most likely find tiny flies or gnats that are capable of breeding indoors and can be a problem in a home year round, given the right conditions. We like to call this group  “wet gunk gnats” because the larvae all have similar feeding requirements of moist rotting organic material. These flies are about 1/8-inch long and look very similar to the untrained eye.

  1. Drain (moth) flies – As their name implies, these gnats are most often associated with scummy drains in sinks or tubs. The wormlike larvae live down in the drainpipe and feed on the gelatinous goo that collects there. Adult flies hover above drains or rest on nearby walls. Drain cleaners, bleach, or boiling water won’t kill the larvae; professionals use special bacterial or enzyme cleaners. See Scummy Drains Can Mean Drain Fly Problems.
  2. Phorid (humpbacked) flies – These gnats can also be associated with slimy drains, dirty garbage cans, rotting plant material, pet feces, and other sources. Heavy infestations in homes are often traced eventually to sewer line breaks. See Phorid Flies Have Terrible Dining Habits!
  3. Drosophila (fruit) flies – Most people are familiar with fruit flies. These gnats are most often associated with overripe or rotting fruits or vegetables. Eggs or larvae may already be inside the produce when you buy it. Since our winter produce comes from warmer, tropical regions, fruit flies can be introduced into your home even in winter. See Where Are These Fruit Flies Coming From?
  4. Fungus gnats – These gnats are somewhat different. In winter, they are most often associated with overwatered houseplants. The larvae live in damp potting soil and will die if the soil is simply allowed to dry out between waterings. The adults run on surfaces in a jerky manner. See Fungus gnats Are Common Where There Are Potted Plants.

Give Colonial a call. One of our trained technicians will inspect your home for the source of the flies and can advise you on steps you can take to eliminate the breeding source. We can kill flies that are present and will follow up if new flies emerge…guaranteed.

Photo Credit : By Luis Miguel Bugallo Sánchez (Lmbuga Commons)(Lmbuga Galipedia) – Commons., CC BY-SA 3.0, Link



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