If you believe that the flies are fungus gnats, that indicates moisture. Sometimes they pop up after overwatering and/or poor drainage. To control, let the soil dry out down to 1 or 2 inches, and if your plants can stand it, do that between each watering. Yellow sticky traps will lure the adults, helping to prevent the females from laying more eggs. The adults do not damage the plants, but the larvae can. If your room is humid with no ventilation, then you might want to open the vent to allow some air circulation (which helps to prevent diseases, too), as long as the vent is not allowing very cold or hot air to come in. Hope this helps!
If you believe that the flies are fungus gnats, that indicates moisture. Sometimes they pop up after overwatering and/or poor drainage. To control, let the soil dry out down to 1 or 2 inches, and if your plants can stand it, do that between each watering. Yellow sticky traps will lure the adults, helping to prevent the females from laying more eggs. The adults do not damage the plants, but the larvae can. If your room is humid with no ventilation, then you might want to open the vent to allow some air circulation (which helps to prevent diseases, too), as long as the vent is not allowing very cold or hot air to come in. Hope this helps!