I tried Borax with sugar as bait but these ants are not taking it. They wonder aimlessly on ceiling, they come from an electrical junction box in kitchen. There is no visible path it's just circling each other in a specific area on ceiling. I bug sprayed the area but they still go there. There are like dozen visible ants.
Kitchens – How to get rid of ants on ceiling
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Caulk the hairline cracks. Pick out the nail pop plaster, screw the nail or screw back in with an adjacent screw to hold it in, spackle & prime. Then, re-paint the ceilings with a Sandy Paint or Add Sand to any paint.
Roll-on the new paint for everything. But then, go back with a brush to do a 2nd or 3rd coat with a brush. The brush will let you swirl & build-up any flat areas for a pretty perfect match quite easily.
A pesticide would not be sold for home use if it were harmful to children in trace amounts. They are generally safe if used correctly. Take for example Maxforce FC Ant Killer Bait Gel, the bait that I often use to control ants. It uses Fipronil at a concentration of 0.001%. When I first started using this bait, I was a little freaked out, because I had to order the stuff online. They didn't sell it in the stores. Then one day I happened to look at the label of the Frontline Plus flea treatment that I apply liberally to my dog each month. Turns out that it contains 10% Fipronil! I did some research, and found out that Fipronil is selectivly harmful to insects (I still don't want it on me though).
Other insecticides are similar. When applied as instructed, they will not be harmful to humans. The best news is that you don't have to take anyone's word for it. Each of these insecticides have a Material Safety Data Sheet (MSDS), which will tell you how and in what concentrations the chemicals are harmful to humans. Just search for the product you are using and "MSDS".
Best Answer
You can powder a 3-6 inch border around the outlet box on the ceiling with diatomaceous earth (I'd use food grade since this is in the kitchen) to control the ants. Then I'd use a fire-rated putty to seal the outlet box.
When I lived in an apartment, there was a large colony of ants living by the pool and they would come out of little cracks in the walls. I ended up caulking everywhere I saw a crack or hole and powdering around all the doors windows and that stopped them.