Food safety has to deal with pests that pose a risk to your food, including flies. The enterprising little fly likes to go after anything it can get, including food, feces and garbage. As a result, it brings a lot of challenges to your food in the form of the germs that it picks up on its adventures.
While flies are found in many varieties, there are two main groups: the filth fly (also called the horsefly or house fly), and the fruit fly (also called the drain fly or gnat). Both pose a risk, but the filth fly is the greater risk of the two.
Here’s the issue:
Filth flies are attracted to any kind of what they would call food with an aroma. They like garbage, dog feces, stagnant water, and – oh yes – your lunch. When they land on the bad stuff, they pick up some of it on their legs and bring it to your food… enjoy!
A filth fly’s mouth looks like a soda straw. So it can’t chomp into your burger like you do. It lands on your bun, spits on it, uses its legs to mash up what it just spit on, and then sucks it back up through its soda-straw mouth. At the same time, it can transfer E-coli, Salmonella, Listeria, Norovirus, or any number of other bacteria to that hamburger you’re about to eat. Like many pests, a fly doesn’t have any bladder control, so it might also leave excrement on your bun! Hungry yet?
A fruit fly may not pose as high a risk, but it is attracted to and often breeds in drains – which always have germs living inside them. Fruit flies are mostly a nuisance, but if you find them inside your food, dispose of the food.
How do you control flies? It depends on your situation. If you’re picnicking, you might want to put screens or nets over your food to help prevent flies from landing. You might also consider fly repellents, but be very careful about using any chemicals around food (whether you’re outside or in!). Try to have your picnic away from garbage cans. The flies might be attracted to the trash, see or smell your picnic, and take a detour.
Inside, keep windows and doors shut, shoo out any flies that might get past you, and use chemicals (wisely!) if you have a serious situation. One or two flies might not be too bad, as long as they don’t decide to come to the dinner table or kitchen, but try to get rid of them. The traditional fly swatter may work, but if you are successful, then clean the area where you swatted.
One person I know keeps a Venus flytrap plant growing in her kitchen. It has helped rid their kitchen of flies for years.
If you notice fruit flies in your home, check your counter for rotting fruit. Keeping your disposal and sinks clean in the kitchen and bathroom can also help you control fruit flies.
Here’s an old wives’ tale that seems to work to get rid of fruit flies: put about ¼ inch of water (about ½ centimeter) in a saucer. In the middle of the saucer place a small bowl of strong wine or vinegar. Let it sit out on your counter top, especially when you’re away from the kitchen for a day or so. The fruit flies will be drawn to the smell of the vinegar, and will drown either in the vinegar/wine or in the water around it. It’s worth a try.
A filth fly’s mouth looks like a soda straw. So it can’t chomp into your burger like you do. It lands on your bun, spits on it, uses its legs to mash up what it just spit on, and then sucks it back up through its soda-straw mouth. At the same time, it can transfer 
Inside, keep windows and doors shut, shoo out any flies that might get past you, and use chemicals (wisely!) if you have a serious situation. One or two flies might not be too bad, as long as they don’t decide to come to the dinner table or kitchen, but try to get rid of them. The traditional fly swatter may work, but if you are successful, then clean the area where you swatted. 
