Harris Diatomaceous Earth Powder Duster (1 lb)

The long version / deep dive

The second line of defense

The Terro bait stations take care of the ants already inside, but I needed something to stop new ones from getting in. Diatomaceous earth (DE) is the answer — it's made of fossilized diatoms that are microscopically sharp. To insects, crawling through DE is like crawling through a field of razor blades. It cuts their exoskeleton and they dehydrate.

Unlike chemical sprays, DE is safe to use indoors around kids and pets. When you have a toddler, that matters.

How it works

The Harris bottle has a squeeze-bulb duster tip that lets you lay down a thin, even line of powder. I put a line in front of the door and along the windowsills. The result? Zero ants crossed that line. Not one.

A line of diatomaceous earth powder along a door threshold — A thin line of DE at the door — ants won't cross it.

The funny part

After I bought this, I realized something: diatomaceous earth is exactly what I use in my swimming pool filter. I've got 40 pounds of it sitting in the garage. The Harris product is the same stuff, just in a smaller bottle with a better applicator.

If you don't have a pool, definitely get this. If you do have a pool, grab the applicator bottle and refill it with your pool DE.

The bottom line

DE is the safest, most effective indoor ant barrier I've found. Combined with Terro bait stations inside and an outdoor Talak perimeter, I've finally won the war against spring ants.

Harris Diatomaceous Earth — razor blades for insects (and the same stuff I use in my pool filter)