Problems with flies are very uncommon with Separett toilets. However, flies may enter the toilet if you leave it for a week or so with the fan switched off and the container with solids still in place. If flies do get in to the toilet, change or empty the container, clean it thoroughly, and use fly spray on the toilet and container several times during the following week to remove any remaining larvae. Never add bark, coir or sawdust because it can contain larva which can develop problems with flies. Remember that flies will not enter the toilet through the ventilation pipe as mesh barriers are in place.