How to Kill Bugs Under a House Slab

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Things You'll Need

  • Push broom

  • Polyurethane sealant

  • Caulking gun

  • Insecticide powder or spray for crawling bugs

  • Rubber gloves

  • Respirator

Insect infestations need regular prevention techniques.

Insect infestations can result in damage to the foundations of your home, so it is important to identify, treat and prevent problems quickly. Concrete slabs are prone to harboring insect infestations because of the construction engineering of the foundation. A slab lies on a thick layer of drainage aggregate over solid ground, and over time a house settles and produces cracks in the slab. The cracks attract insects to form nests under the slab in the moist and dark atmosphere. Regular maintenance checks and pest control techniques can help to reduce infestations so you can prevent further substrate damage.


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Step 1

Identify the type of insect infestation you have under the slab by looking for the insects around the perimeter. Common bugs include ants, termites, sow bugs and pill bugs. Check with local authorities if you find termites because codes may require a licensed pest controller with this type of infestation.


Step 2

Remove all leaf litter and decaying wood or dead vegetation from around the perimeter of the slab by three feet. Use a push broom and sweep around the perimeter to clear all debris. This removes an easily accessible food source for the insects.

Step 3

Look carefully at the sides of the concrete slab and check for evidence of cracks. Look on top of the slab for cracks if you have a crawl space. Use polyurethane sealant and a caulking gun to caulk into all cracks to seal insect entry points.


Step 4

Check the entry points of pipe work into the slab, and caulk around the pipes to seal them. Caulk around pipe work from inside the house to prevent insect access into the home in places such as the kitchen and bathroom.

Step 5

Dig up and move all annual and deciduous perennial plants that surround the slab to prevent constant sweeping up of fallen vegetation. Check that no trees are close to the slab, because tree roots cause damage to a slab and create further cracking over time.


Step 6

Apply a two-inch wide layer of crawling bug insecticide powder or spray around the perimeter of the slab to kill any bugs that walk over it from or to the slab. Reapply the insecticide to dry ground after any rainfall.


Apply insecticide on a dry and calm day to avoid chemical drift by wind or rain.


Wear rubber gloves and a respirator when applying insecticide to avoid ingesting the chemicals.