These tiny bugs keep getting in my bathroom. There are no gaps or holes anywhere I think they just get in from the fly screen.
Hi @Accomplished_B,
If the insects are coming in from outside, I'd start by having a very close look around the exterior of the window rather than just the flyscreen. Tiny insects can make their way through surprisingly small gaps around the window frame, sill and where the frame meets the surrounding wall.
Any gaps you find around the outside could be sealed with an appropriate exterior sealant such as https://www.bunnings.com.au/sika-300ml-white-sikaflex-11fc-purform_p0628965 . I'd concentrate on sealing the exterior rather than the interior, as this stops the insects before they can get into the window assembly. Just be careful not to seal over any drainage slots or weepholes in the window frame.
Another possibility worth considering is drain flies, particularly as you're finding them in the bathroom. Drain flies are small flies that breed in the organic buildup that can develop inside drains. If they seem to be concentrated around the shower, basin or floor waste, the drain itself could actually be the source rather than the window.
If that's the case, the important thing is to remove the organic buildup they're breeding in. Start by removing any accessible hair, soap scum and debris from the drain. You could then use a suitable drain cleaner, following the manufacturer's instructions carefully, to help break down the buildup further inside the pipework.
Once the drain cleaner has been used and thoroughly flushed away according to its instructions, regularly flushing the drain with very hot water can help remove remaining organic material. Simply killing the adult flies won't solve the problem if larvae are still developing inside the drain, so cleaning the drain thoroughly and repeating the process if necessary is the important part.
As a quick test, you could cover the drain overnight with some clear tape, leaving a small amount of space for airflow. If you find flies trapped underneath it, that's a pretty good indication they're emerging from the drain.
Let me know what you think and if you have further questions, please don't hesitate to ask.
Jacob
