Why do biting midges appear in the house?

By PestArchive · Updated 2026-06-19

PestArchive is an independently run household-pest reference, compiled and translated from public sources for educational use only.

Why do biting midges appear in the house?

Biting midges do not appear for no reason. Their presence has only one cause: there is a damp environment in the house suitable for them to breed.

Most common breeding sources

  1. Standing water in plant pot trays, the number one source of indoor midges. Water sitting for more than 3-5 days allows larvae to develop.
  2. Drains and floor drains, grime and grease on pipe walls, combined with dampness, are ideal breeding grounds for midge larvae.
  3. Garbage bin bottoms, liquid from kitchen waste accumulates at the bottom, breeding adults and larvae.
  4. Bathroom dead corners, under the sink, behind the toilet, and shower floor drains, these damp, dark areas are prone to breeding.
  5. Balcony standing water, from air conditioner condensation, rain accumulation, or excess watering that does not dry out.

Outdoor sources

  • If the home is near ponds, wetlands, ditches, or green belts, midges may also fly in from outside.
  • Lower-floor residents (1st-3rd floors) are more susceptible to outdoor midges.
  • Homes with yards may have weed and leaf piles as breeding sources.

Solution

Remove standing water, keep things dry, regularly clean drains and floor drains, and spray dinotefuran-containing household insecticide on corners and window sills. Midges will disappear quickly. The key is to persist for 1-2 weeks, midges have a short breeding cycle, and once the environment improves, newly hatched midges will have nowhere to breed and will disappear.