While you can see ants and avoid them, it's not always possible to see, taste or smell dangerous bacteria that may cause illness if food is mishandled. With great weather and holidays, picnics are in season. However, it's also the season when more people become ill from foodborne bacteria. So, food transported without an ice source or left out in the sun at a picnic won't stay safe for long. That way, you won't have to worry about the storage or safety of leftovers.
Clean preparation is essential.
Foods cooked ahead need to be cooked in plenty time to thoroughly chill in the refrigerator. Pack food from the refrigerator right into the cooler. At the picnic, keep the cooler in the shade. Keep the lid closed and avoid repeated openings. Replenish the ice if it melts.