Fruit flies can be attracted from great distances to fruits and sweets, which produce ethanols from the natural breakdown of their sugars. They’ll slip into any home to get to the source of that ethanol, to feed and lay their eggs on it.
When these fruits and sweets have been left out for your spirits, this can get annoying.
It seems counterproductive to cover the offerings, because it adds a challenge for your spirits to get to it. But it’s an affront to let the flies get to the offerings before the spirits can. And of course, fruit flies aren’t the only vermin that might get attracted.
So how do you effectively leave out offerings for your spirits?