I set up my new Flow Hive Brood box 2 days ago and place the bees inside. I already had a few ants at the entrance this morning. What is the best way to treat this?
You have several choices. If they are not Argentine ants (depends on where your are in NorCal - Sacramento and north, they shouldn’t be), you can use borax. Just 1/4 cup warm cheap grape jelly with an equal part of warm water, then add in another 1/4 cup borax (I use 20 mule brand). Pour into a small mason jar and poke small holes in the lid with a nail. The nail should be less than 1/8" wide, so that bees can’t reach the mixture. Then put the jar on the ground near the ant trail. It should deal with the ants within a week or so.
The other way is to use ant moats. These are the only method that dealt with Argentine ants for us. Just use the magnifying glass symbol at the top right of this page to search for ant moat.
I just posted my latest concept and how to make an ant moat, in case you decide to go that way.