I like to ferment my juice in an open container giving the yeast plenty of oxygen during the first few days of fermentation.  The issue is that while I want oxygen, I want to keep all foreign objects out, including the fruit flies!  Here is a solution that I found that works great.

Designed as a feed bucket cover, this inexpensive cover works great allowing the bucket to remain open during primary fermentation, yet it keeps the little critters out. Yeast enjoys a rich oxygen environment so many winemakers prefer not to put juice under airlock during primary fermentation.

Use this handy bucket cover during primary and then go under an airlock for secondary fermentation. It’s available in a choice of colors, but know that you will get wine stains so burgundy is my color of choice!