Flea Infestation Guide: How to Kill and Get Rid of Fleas

By Carol McCarthy

Fleas are tiny but the suffering they bring to pets can be huge. The only way to stay ahead of a flea infestation is to practice flea prevention year-round, according to Dr. Cynthia Cox of the Shalit-Glazer Clinic at the MSPCA-Angell Adoption Center in Boston, Mass., and Dr. Cathy Lund of City Kitty, a feline-only veterinary practice in Providence, R.I.

“When you see the adult fleas, that is just the tip of the iceberg as far the life cycle,” Lund says. “At that point, you have a real problem in the house.”

David Jones of Bio Tech Pest Controls in Westerly, R.I, an environmentally friendly pest control business, explains why: The adult flea needs a blood meal (your pet, for example) in order to produce fertile eggs (40-plus per day), which then fall off the animal and drop to the floor, carpet, bedding, etc. The eggs develop into larvae and then into pupae that are protected inside cocoons, which can lay dormant for many months until noise, heat, vibration, light, exhaled carbon dioxide or other stimulation causes them to emerge as fleas to start the cycle again. If you see a flea, you’re likely already in the midst of a flea infestation.

That is why constant vigilance is necessary, Lund says. “It’s like flossing to prevent gum disease and brushing your teeth to prevent cavities. Don’t let it get to the point where you can see a flea.”

To prevent a flea infestation, treat your pet year-round throughout his or her life with flea preventives—typically a topical liquid or oral medication applied or given monthly to dogs and cats. Dosages of topical flea repellants depend on the weight of the animal. Some protect against fleas, fleas and ticks, or other parasites, such as heartworm. Talk to your vet about which flea prevention product is best for your pet.

Cox notes that if you have a cat, it is essential to use the cat-specific version of any flea product, in consultation with your vet. “While many are now over the counter, some contain insecticides with a very narrow margin of safety that can result in the illness or death of companion animals, especially cats,” she says. And never apply flea preventative on cats that is marketed for dogs—and vice versa. 

If your pet has fleas on him, brush the coat with a flea comb and dunk the fleas and eggs in hot soapy water to kill them. Then give him a thorough bath with flea shampoo until no sign of the infestation is visible. Ask your groomer or veterinarian for shampoo advice or have her bathe your pet. After your pet is dry, immediately treat him with flea repellant.

Flea bites can cause real suffering in your pet, with constant itching and scratching that can lead to skin irritation and even infection, especially if your pet is allergic to flea saliva. “They can get super itchy, and the skin can become raw and irritated,” Lund says.

Pets—and people—are also at risk of diseases carried by fleas. For example, the organism that causes cat scratch fever is found in flea poop (dried-up blood) and can sicken your cat and you.

Remember, if the fleas are on your pet, they are in your house. To kill fleas and eggs in your carpet, dust the whole area with food-grade diatomaceous earth (a talc-like powder containing silica and fossilized marine phytoplankton), Jones suggests. “Apply it to all fabrics that you and your pets come into contact with,” he says (consider wearing a dust mask). “Then, vacuum, vacuum, vacuum!” If applying diatomaceous earth isn’t practical, just thoroughly vacuum all your floors, carpets, and upholstery.

Your vacuum cleaner actually is the best way to get rid of adult fleas, eggs, larvae and cocoons in the carpet, Jones says. Just be sure to immediately take the vacuum outside to remove and dispose of the bag. Do not leave the bag inside the house, he stresses. Vacuum repeatedly until you see no evidence of a flea infestation.

Fortunately, fleas cannot survive the “hot” cycle of the washing machine and dryer, Cox explains, so wash sheets, pillowcases, duvet covers and comforters with detergent and dry all of it on the “hot” setting. Be sure to also wash and dry all of your pet’s bedding, plush toys, etc., on the “hot” cycle. Treating pet bedding with flea repellant (usually a powder) can also be helpful.

Make sure to vacuum your mattress thoroughly. Again, dispose of the vacuum bag immediately.

Making your yard unwelcome to fleas is the best way to keep them at bay. Fleas thrive in moist places, so do not over-water your lawn, Cox advises. Also keep the yard free of debris that captures moisture, like grass clippings. And choose landscaping products that deter them. “Fleas have an aversion to cedar chips, so using them around shrubs and pathways is an excellent (and natural) way to reduce the flea population,” Cox says. Adding beneficial nematodes to your yard is another effective, natural form of flea control.

Jones says a pest-control professional can treat grass and vegetation with plant oil insecticides that kill fleas and ticks but will not harm you or your pets. A repeat treatment might be needed six to eight weeks following the initial one. Costs vary depending on the size of the area treated, says Jones.

To keep fleas from returning, get an external treatment in early spring and fall, he advises.

Read more about treating fleas and ticks in your yard.