Looking for a way to combat pests naturally? Here’s why you should consider nematodes. 

When it comes to flea control, a lot of people assume they only need to take care of their animals and the inside of their homes. But when the weather turns warm, fleas also multiply and thrive outdoors. During the summer in fact, depending on where you live, your lawn and garden can become a haven for these troublesome pests.

Adult female fleas lay their eggs on host animals. If a stray dog or cat with fleas passes through your yard, these eggs are shed in the grass and soil, where they hatch into larvae and mature into hungry new fleas. Next time your companion is out taking the air or sunbathing on the lawn, the fleas jump aboard and are brought into the house where the cycle starts all over again.

Spring is the best time to start preparing for flea season, and this should include extending your control strategy out of doors. An effective, non-toxic way to do this is with beneficial nematodes.

What are nematodes?

Nematodes are tiny, naturally-occurring predators that live under the surface of the soil. Seen under a microscope, they look like short, non-segmented worms. There are thousands of different types, but Steinernema carpocapsae is most effective for controlling fleas. Unlike chemical pesticides, these nematodes do no harm to animals, people, birds, plants, other beneficial insects or the environment, but can be used in large numbers to destroy fleas over a wide area.

When you consider the negative impacts of using chemical pesticides on your lawn, nematodes make good sense.

Nematodes kill fleas by entering their larvae through body openings or even penetrating the body wall. Once inside, they release a bacteria that destroys the host. (This bacteria is harmless to other organisms, including people and animals.) The nematodes then feed and breed before leaving the dead larvae in search of new prey.

How to use them

Like other beneficial insects, nematodes are sold live. They can be bought at some garden centers or ordered online from companies like ARBICO-Organics or Fleabusters. “They’re very easy to apply,” says Robert Yarmuth of Fleabusters. “You just use a hose-end sprayer, drop the sponge in and the water pressure will release the nematodes from the sponge.

Fleas can build up immunity to pesticides, but not to nematodes.

Nematodes like moist conditions, and are sensitive to heat and sunlight, so it’s important to take a few precautions when applying them to your yard. Be sure to also carefully read the product instructions. They should be used promptly after purchase. “Put them in the fridge as soon as you get them,” says Robert. “You have a two-week window to release them.”

Additional tips

• Apply nematodes in the spring as soon as the ground is thawed. “Fleas are everywhere, and although they go into a dormant state when the ground is freezing, they start hatching once it thaws,” says Robert.
• Don’t release nematodes during the heat of the day, when the sun is high; do it in the early morning or late evening, when temperatures are cooler and the sun is low.
• Make sure the lawn is moist before application. If the weather has been dry, soak the area with a hose or sprinkler first.
• “Fleas are light sensitive, so focus on the shadier side of the house and under vegetation,” says Robert. “Fleas are more apt to be found there than in direct light.”
• Water immediately after application to help the nematodes move into the soil. “If there’s no rainfall, water the grass again once or twice a week after that. Lack of moisture will kill them.”
• Nematodes start destroying flea larvae within a day of being introduced to the environment, but it takes a couple of weeks for them to take full effect. “They should last about 90 days,” says Robert, adding that subsequent applications every quarter may be required.