Controlling Fleas with Nematodes

We’re always looking for organic ways to control pests in our yard and home. Fleas are an especially troublesome warm weather problem but one that we’ve been able to keep under control using beneficial nematodes. These microscopic round worms are safe for your family and your pets but kill fleas (as well as weevils, cranefly, grubs, corn borers, and other bugs that dine on vegetable gardens.)

The nematodes are microscopic so you won’t see them; you’ll purchase them on a small sponge like the blue sponge on the right. This sponge contacts about one million live nematodes, enough for about 3,000 square feet of yard space.

We purchased the nematodes at our local garden store or you’ll find this same product at March Biological Control — if you order nematodes from outside Washington State or Oregon, you’ll need to have it shipped via Second Day Air.

Once purchased, the sponge (which costs about $15-$20) containing the nematodes has to be handled carefully. It can’t be exposed to sunlight and should be refrigerated until it is used. You can purchase the nematodes up to about seven days prior to application on your yard.

You’ll want to apply the nematodes at a time when your soil temperature is between 40 and 90 degrees (which, for us during the Texas summer, means early morning or late evening.)

To apply, soak the sponge in about a gallon of room temperature water, taking the sponge out and soaking it completely (rinse the bag in the water, too, in case any of the micro critters are attached to the inside of the bag.) Stretch the sponge, stretch it, squeeze it…basically try to get everything you can out of the sponge.

We used a sprayer on our hose to apply the nematodes to the yard, spraying the soil. You’ll want to keep the soil watered. If fleas return, reapply in about eight weeks.

We’ve used nematodes the past several summers and had excellent results, helping keep our dogs flea free!

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About Paris Permenter

Paris Permenter is the founder and co-publisher of LT Media Group LLC. Along with her husband, John Bigley, she edits,, and has authored over 30 books on pets and travel.

  • Don’t forget to treat your pets for fleas as well. Kill the eggs on your dog and in your lawn. Regular vacuuming will also help prevent flea breakouts.