There are a wide variety of homemade fly sprays. None of these contain ingredients that should be harmful in moderate amounts. However, in my experience, mixes like these are only marginally helpful. They should be used in combination with other fly control methods, including a proper manure management program.

Combine ingredients and use in spray bottle.

Fly Repellent 1:
2 cups white vinegar
1 cup water
1 cup Avon Skin So Soft
1 Tablespoon eucalyptus oil

Fly Repellent 2:
Combine ingredients and use in spray bottle.
2 cups mineral oil
½ cup lemon juice
2 tsp. citronella oil
2 teaspoon eucalyptus oil
2 teaspoon lemon dish detergent

Fly Repellent 3:
Combine ingredients and use in spray bottle.
1 cup cider vinegar
1 cup water
1 oz citronella oil
2 oz Avon Skin So Soft