I rent a 1-bedroom apartment on the 9th floor of a highrise. I've been trying to solve an ant problem over the past two months, including three bouts of commercial bait that is suppose to eradicate the colony. The problem only abates for a few days. The landlord has already brought in a pest control expert a week ago, who merely dabbed some gel at two spots (kitchen and bathroom). The problem remains unchanged, despite hieghtened vigilance in cleaning (I'm was already a clean freak beforehand). I may have to ask for fumigation. I believe that the landlord would be justified in inspecting neighbouring apartments, but that's not within my control.

From what I've researched online, an ant problem might be an ongoing management problem.

The question

As a means of mitigating the problem, prior to actually getting it under control, would it be advisable to:

(1) Caulk up the junction between the baseboards and the wall, between the shoe moulding and the baseboard, and between the shoe moulding and the floor?

(2) Caulk up or re-caulk the junction between the kitchen counter and the wall, and between the washroom vanity and the wall?

My thinking is that restricting their mobility makes their life and survival more difficult, but I am also concerned that it may reduce the effectivenes of other measures. For example, it may interfere with their bringing bait back to the colony, or make satellite colonies more likely. Or it may impede fumigation, if that happens.

  • 2
    Caulking is unlikely to be a final solution, ants can squeeze through the tiniest of openings, and there a likely to be hidden openings that you can't access. Different species of ants require different treatments, the "expert" should know, but sometimes they don't. Their size and what they are attracted to can help determine the species. – Mattman944 Sep 14 '19 at 23:19
  • OK, thanks. They are 1.5-2mm long, gray/tan colour. I wasn't thinking about caulking to vacuum seal the place, but just to impeded their mobility. Wondering if that strategy might backfire in the manner that I described. – user2153235 Sep 14 '19 at 23:33
  • 1
    Assuming you find the right type, bait is you best bet. – Jasen Sep 15 '19 at 6:29
  • I posted a species identification question at this Stack Exchange page. Thanks. – user2153235 Sep 15 '19 at 14:36
  • use boric acid on them. it might take a few months (literally) to kill all the (sub) colonies of all your neighbors, but it will work. leave the bait around later so that any fresh ones get hit right away. – dandavis Sep 16 '19 at 5:38


you'll need a <=1 gal sprayer and mix rate up to ~1 ounce per gallon. spray the entire place, let it dry.

another one is permethrin, in Martin's Cyonara.

both can be gotten at tractor supply, or amazon, sometimes at depot/lowes.

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  • Thanks, Ron, but I have to work with my landlord company and its exterminator. I found out that the infestation affects my neighbour below as well. So far, the exterminator is going with the slow route of bait to exterminate the colony/colonies. They might choose fumigation later. This was more a question of whether caulking would actually improve the management of the ants while the bait works, which apparently can take months, or whether the caulking will backfire in the manner that I describe.d – user2153235 Sep 17 '19 at 23:48
  • a professional [honest] exterminator would simply spray bifen. For < $20 u can spray it yourself it would be easier and cheaper than caulking. a $10 8-oz bottle of bifen will last u years for just spraying your place. let me guess terminix? baits = recurring visit = moneymaker. spray bifen or cyonara around entire perimeter of your apt, ants cross it they die, effective for 1-3 months, quite simple. once dry bifen & cyonara is safe including in food areas [kitchen cabinets but don't directly spray your dishes] – ron Sep 18 '19 at 15:22
  • Hi, Ron, I marked "up" your answer, but didn't mark it as the answer because it answers a slightly different question. Thanks. – user2153235 Sep 19 '19 at 0:58

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