We just moved to California, and specifically one of the many areas that has a major problem with Argentine Ants. The house we're renting is relatively new (1980s construction), but it seems like it has sealing issues - there are lots of unsealed corners, tiny holes in the baseboard where moulding meets, that sort of thing, where ants can get through.

Thus, ants come out of these corners, through the back corners of cabinets, etc., and when we get one spot under control (usually a few days of Terro [sweet solution of Sodium Borate aka Borax] takes care of one group) another comes from a different invisible hole in between the baseboards, or the cabinet, or similar spaces.

These aren't always exterior walls, either; though so far they're all at least relatively close - a few feet from an exterior wall. We're talking hundreds of ants at a time - long trails finding whatever they can (the cat food, the trash can, a crumb my kids dropped, etc.) pop up overnight.

Is it worth attempting to "seal" each place where I see ants coming in? Or will they just find another way in, perhaps somewhere I don't see until they've covered my pans or something else and made another mess for me to clean up. If it isn't, is there another option beyond hoping the Terro (or other similar baits) work eventually - or is this the realm of the professional [or just hopeless]?

And if it is worth attempting to seal the gaps in the baseboard, what's the best solution - caulk? Liquid sealant?

If it's relevant, there is no basement, but I don't know too much more about what the house is built on (we can see a crawl space under the furnace, though); so it's possible the ants are in the ground below us, or it's possible they're inside the walls. We're renting, so we'd prefer to do less damage to the walls if possible. Ant control in California is mostly the tenant's issue, though we have had issues since we moved in so we may be able to push back on the landlord - but we'd like to try non-invasive solutions first.

  • 1
    Step 1 - leave no exposed food and water in everywhere around the house, and place ant traps on high ant traffic areas. Step 2 - inspect the exterior enclosures for seams, gaps, cracks, and seal the defects. Step 3 - hire an exterminator to perform periodic spray.
    – r13
    Sep 17, 2021 at 19:13
  • Step 1 done to the extent possible (we have a cat, who needs water/food... and children). Step 2, though, is outside what we can really do - we rent, and I'm sure there's lots going on that way; but we undoubtedly have internal ants, no, given the locations (not only exterior walls)... hence my question of whether it's worth sealing the inside.
    – Joe
    Sep 17, 2021 at 19:18
  • 1) It really means clean your house to the extent you can. 2) As long as there is an entrant path, the ants will get in then hide somewhere not likely to be noticed and disturbed to breed. You can try sealing indoor gaps though if insisted upon, but likely to be to no avail. Rental? I am adding step 4 - move, if unbearable or too costly for prevention.
    – r13
    Sep 17, 2021 at 19:35
  • Hmm, sounds like an answer there :) I'm not sure how easy it would be to seal up the outside... the siding comes to about a foot off the ground (concrete base, I think, or cement block? Something non-wood) and I can feel behind the siding wood, insulation paper, etc. - there's no "seal" below it, so I assume ants have no problem getting up that.
    – Joe
    Sep 17, 2021 at 19:46
  • No single step is guaranteed, but if carried out all 3, the chance is much better and "given some time" to be effective, unless the house is near, or above, an ant nest. Done that several ago without the need for the third step.
    – r13
    Sep 17, 2021 at 20:11

1 Answer 1


Keep at it.

This is how our San Diego house was when we moved in. At least 4 different sources of Argentine ants. I remember an impressive trail to a dish of butter left out. We had spiders inside living on the ants which was kind of neat.

1: Put out ant traps. I bought a bunch of different kinds and then more of the brand I saw most ants going to. If I remember I had luck with MaxAttacks.

2: When the ants were really hitting a trap I sprayed ant spray on the floor past it but left a clear path to the trap and back. Ones that skipped past the trap would die. Not sure that is needed but that is what I did.

3: Repeat.

Those traps work. After a couple of weeks we were done with ants inside.

Strangely enough after we lived there a year we were done with ants outside too. I think the prior owners were spraying the lawn with something that killed bugs, but killed ants less well.

  • 1
    Most traps these days are bait stations, which contain poisonous bait that the ants take back to their queen. If you have enough, then it's likely the ants took a significant quantity back to the queen and the queen died. That will usually result in all the other ants dying/leaving, too.
    – TylerH
    Sep 20, 2021 at 21:08

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