Recently my house has had an ant problem. I'm plugged up the holes I think they're coming in from but I still see them wandering around the house and getting into my food.
How do I get rid of them without professional help?
This really really depends what type of ant.
Most you can just keep spraying til they give up, die off or decide somewhere else is more profitable.
Destroying their pheromone paths will prevent hungry returnees. Killing them in your house will prevent them returning to the nest to set a pheromone path to your comestibles.
Things which are smelly &/or sticky make good path-breakers. Vaseline they will not cross even though they can still smell the other side of the path. Hairspray works for a day, then loses its potency. Lighter fluid washes the path away, but doesn't prevent their return & is also a bit flammable ;)
Pharoah ants, on the other hand, can only be killed by feeding them with a hormone which prevents their breeding. If you try to kill/spray/squish pharaohs, they go into 'under attack' mode & all turn into breeding females & dissipate - not what you want - you will end up with tiny nest sites everywhere.
[This, strangely is not borne out by the wikipedia link - but was what I was told by the exterminator who came to rescue us from an invasion we were unable to deal with ourselves after 6 months of poisoning & the methods described above, which have been pretty successful on every other ant-type. It may have just been a poor or misinterpreted version of the 'budding' which that page does discuss - nevertheless, pharaohs need specific pharaoh 'poison'.]
I've used TERRO Liquid Ant Killer to successfully kill ant hills. Not in accordance with the instructions, I tore up the visible anthill, waited for ants to start appearing, then poured the product directly on them and covering most of the major holes.
I've also read about mixtures of honey and borax, and lots of other solutions on Google. From what I understand, most of the store-bought liquid ant killers are simply a mixture of borax and something sugary.
I've also heard that powdered cinnamon will coat the ants and either break down the joints or exoskeleton, causing them to die, or it hardens on them like cement.
If you want some art work and have access to a decent furnace, pour liquid aluminum down the ant hill. The aluminum goes quite a ways into the hill before solidifying. Digging up the cooled aluminum makes for a very interesting sculpture. Look it up on YouTube for some of the amazing structures people have gotten from doing this.
More (or less) on heat, you can supposedly pour boiling water into the anthill to kill everything. It'll take a large pot of water, but it's more environmentally friendly than most of the other options you'll find.
Wiping down surfaces with white vinegar will help remove their trails. Supposedly they hate the smell of vinegar. I put an open bottle of vinegar under my kitchen sink, which was an entry point for the ants, and got rid of them from my apartment fairly quickly. The bottle only had a few ounces in it, so it eventually evaporated, but I didn't notice any vinegar smell while it was fresh. Of course, my landlord was also spraying for ants, so vinegar wasn't the only factor here.