We had carpenter ants - they are big and black., You may be able to hear a clicking sound like 2 fingernails hitting each other if you are near where they are working, or you may see saw dust on the ground.
We put out bait traps. The problem did not go away. After having to replace an entire window frame, we got an exterminator. They fixed the problem, but we were sorry we didn’t get professional help sooner.
Not all big black ants are carpenter ants. Mine are definitely not.
I only use the non toxic spray in the house. H sprays Terro around foundation after I spot them in the house.
My W once gave me a great idea to get rid of ants by telling me not to leave a jar of PB partially open ever again.
I found this product very effective. Sprayed the area once, never saw the ants again. But I still spray once every few months, just to be safe.
Speaking of PB, we once had a mouse infestation in the garage. PB- loaded traps worked great to take care of the mice, but the traps began to attract ants. Mr. B mixed some boric acid in the bait PB - problem solved. No mice, no ants. 
Had ants- dead ones killed by the indoor and outdoor Ortho Home Defense spray. Also had nests outside- used a granule on them I found at Lowes/Home. Do need to know type- sugar/wood eaters need different solutions. Renter- let owner know and have them take care of it. Also caulk entry points can be helpful- eg cracks from outside.
I second Terro bait. We had an ant infestation in our house when we first bought it. I picked up a box of it at Home Depot for around $13. I opened it and put some bait packets next to a place where I saw some ants. I had to put a little drop of bait on the floor to tempt them a little. The next day the bait packets were swarming with ants. Over 2 days, the swarm got thinner and thinner until they were all dead.
Neighbor had carpenter ant damage. They had the damage repaired and was able to purchase specific product from a local source. Having that information, we noticed carpenter ants around our big cedar tree which is a good distance from our house and purchased the same product from the local source.
Some parts of the country have termites, and there has been a shift on those to having bait traps versus the toxic soil stuff.
Having the correct ID of the insect and the most effective local treatment is key.
Ants are very annoying, but having the poison get to the queen is key through all those worker ants.
@wis75 yes Home defense is a good product. I’ve used it over the years for spiders, waterbugs etc.
borax with sugar and water worked for us last year, after we left a plate with this stuffs in laundry room, no more big ants were seen the next day and all summer last year. Traps didn’t work for us the previous years.
I tried the boric acid with sugar and it’s not working, so I’m going to try Terro.