There isn’t a one-size-fits all recommendation for exactly how much to add. There are various factors, like how many people use your toilet, using different bulking material (sawdust, peat, or coconut coir), and the type of unit you own. [3] X Research source

Leave the fan off after application so the flies will land on it and meet their doom. Diatomaceous earth is made from fossilized diatoms. Although it looks like a soft powder, the material is very sharp for tiny insects![6] X Research source Only use diatomaceous earth that is labeled “food-grade” or “natural-grade,” not the kind used to filter swimming pools. The pool-grade powder contains more silica, making it more dangerous to use. [7] X Research source Wear protective gear, including gloves, safety glasses, and a dust mask when spreading diatomaceous earth. The dust can irritate your lungs if it’s inhaled. [8] X Research source

Neem oil is a natural, botanical insecticide that kills insects by suffocation.

Multiple applications are necessary since you have to wait for the flies to land so you can spray them. Check the label; some insecticides add other pesticides which could be harmful to your compost. Pyrethrin is made from compounds extracted from finely powdered daisies. [13] X Research source

Empty the jar outside and replace the fruit bait after a few days.

Empty the bowl every few days for a week or two, or until the infestation clears. Stick with apple cider vinegar; flies aren’t fans of white distilled vinegar.

To make a bleach solution, mix 1 ¼ tablespoons of bleach (18. 48 mL) with 1 US-quart (950 mL) of water in a spray bottle. Keep the fan unit dry; carefully remove it before cleaning if possible. Otherwise, be very careful not to get the electrical components wet. [19] X Research source Use a brush with stiff nylon bristles and a flexible wire handle to scrub your unit. It’s essential that you remove all of the eggs, and this type of brush allows you to get into all of the nooks and crannies.

The ventilation system also reduces humidity and moisture–flies love moist environments, so the fan is a useful deterrent. [21] X Research source

Gasses from mothballs cause health problems like nausea, headaches, and respiratory issues. [28] X Research source