Knowledgebase

What kind of fly is all over my apartment? #855679

Asked November 22, 2023, 6:13 PM EST

Hi there, I live in an old apartment in NW Portland and have been overrun by these small flies since the spring. I've been catching what feels like thousands in these blue light sticky catchers, but I'm swatting at them constantly. I've made sure I have no fruit/food out because I originally thought they were fruit flies. I hoped the cold weather would see their end but unfortunately it hasn't. They don't seem to be in a specific part of my apartment, however I have seen a bunch stuck in spiderwebs near my windows (inside). I would love your help identifying these flies so I can figure out how best to get rid of them for good if I can! For size reference in the photos, here is a link to the trap that they are in: https://zevoinsect.com/flying-insect-trap-starter-kit-model-3/

Multnomah County Oregon

Expert Response

Izzie:

I cannot give you a positive ID but reading your description of the situation I think you likely have Fungus Gnats.

Following are some questions that will help me ID these flies:

  • Do you have plants in your apartment?
  • Do you have any moisture issues in the apartment?

The female fungus gnat can lay up to 200 eggs a week so the numbers can quickly increase.

It appears that their primary food is organic matter and fungi in the soil or planting medium.

If this appears to fit our situation let me know and I can give suggestions on control & management.

Let me know if you have any additional questions. Thank you for contacting us at Ask Extension. Rich

An Ask Extension Expert Replied November 28, 2023, 1:57 PM EST

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