The problem with every summer is that flies have a nasty habit of hanging out on food and on our skin. This is big issue among people as they spread diseases and cause problems about hygiene. Here’s a way to keep them away naturally, without using chemicals, which may be toxic even in humans. Here’s what you’ll need: plastic sandwich bags, salt, lemon juice, and some pennies. A scientific theory lies behind this. Flies fly with the assistance of the direction of the sunlight and by giving the reflection of the pennies they will get distracted and will fly away instead.