Whenever you see a fly, and it's flying frantically, you think to yourself "it'll get tired, that's when I'll strike", but you realize it's taking too long and you get impatient. 6 hours. That's the length of time it can stay flying for; 6 hours. You also might think "I'll leave the fly alone, it'll die out within the week". Maybe you've thought like this, but even this is not legitimate. They can survive for months.