I've placed two FGMO emulsion cords in each of 3 hives on top of the frames and plan to fog tomorrow or the next day as soon as the breeze dies down. In all the reading I've done on FGMO, I don't remember the best time of day being mentioned. Should you fog early in the morning or late in the evening when everyone is home, or , in the middle of the day when the field bees are out? I'm using screened bottom boards so will fog five seconds up through the bottom.
I have addressed this topic before.
I consider the best time to fog late in the day when all the bees are home.
There are several reasons for this.
One: to cover as many bees with the fog as possible.
Two: foraging bees do bring home Varroa from sick and dieing colonies that they rob.
Three: Foraging bees that are fogged at this time will have a film of FGMO, delicate as it might be, that will interfere with mites hitching a ride home with them. Must remember that one of the functions of FGMO is to interfere with the mites ability to cling on to the surface of the bees.
Four: My observations reveal that FGMO stimulates grooming by honey bees, hence fogging late in the day will increase grooming by the bees at a time when their activity lends itself to that purpose.
Of course, this does not mean that fogging may not be done at any time of the day. Management of your colonies depends greatly on your ability to accomodate your work schedule.