Black flies can quickly become a nuisance around outdoor trash cans, but there are several effective strategies to keep them at bay. First, ensure your trash cans have tight-fitting lids to block access. Regularly clean the bins with a mixture of water and vinegar or bleach to eliminate odors that attract flies. Use trash bags to contain waste and prevent leaks. Consider placing a few bay leaves or citrus peels inside the bin, as their natural scents repel flies. Additionally, keep the area around the trash cans dry and free of debris, as standing water and organic matter can attract pests. For extra protection, sprinkle diatomaceous earth around the base of the bins to deter flies naturally. By following these steps, you can significantly reduce the presence of black flies and maintain a cleaner outdoor space.