Chewing lice on cats are tiny, wingless parasites that live in a cat’s fur and feed on skin debris, hair, and surface secretions. The only species of chewing louse that infests cats is Felicola subrostratus. Unlike sucking lice (which feed on blood and affect dogs), chewing lice nibble on the skin itself, causing intense irritation and a rough, unkempt coat.
What Chewing Lice Look Like
Adult chewing lice are only a few millimeters long, flat from top to bottom, and pale yellow to tan in color. They have six legs, no wings, and a broad, rounded head that’s wider than the body segment behind it. That wide head is a distinguishing feature: sucking lice, by contrast, have narrow, pointed heads. You can sometimes spot them with the naked eye if you part the fur under bright light, but a magnifying glass or fine-toothed comb makes them much easier to find.
Female lice glue their eggs (called nits) directly onto individual hair shafts close to the skin. Nits are tiny, teardrop-shaped, and white or yellowish. They stick firmly to the hair and won’t flake off the way dandruff does. If you see small white specks in your cat’s coat and aren’t sure what they are, try brushing them with your finger. Dandruff slides off easily. Nits stay put.
The entire lifecycle happens on the cat. Eggs hatch into nymphs, which molt twice before becoming adults. There is no pupal stage. Because lice spend their whole lives on the host and cannot fly or jump, infestations tend to build gradually rather than appearing overnight.
Signs of a Lice Infestation
The earliest signs are scratching, biting, and rubbing at specific areas of the body. Cats with chewing lice are often restless and will groom obsessively at irritated spots. As the infestation progresses, the coat may look dull, dry, or matted. Hair loss can develop in patches where the cat has been scratching or where lice are concentrated.
In severe cases, repeated scratching breaks the skin open, leading to small wounds and bacterial infections. You might notice scabs, redness, or a musty odor from infected sores. Kittens, elderly cats, and cats with weakened immune systems are especially vulnerable to heavy infestations because they’re less able to groom effectively.
How Cats Get Lice
Chewing lice spread through direct contact with an infested cat or through shared bedding, blankets, and grooming tools. They cannot jump or fly, so transmission requires close physical proximity. Stray and outdoor cats that interact with other cats are at higher risk, as are cats in shelters or multi-cat households where bedding and brushes are shared.
Lice are species-specific. Felicola subrostratus infests only cats. It cannot survive on dogs, and it cannot infest humans. If your cat has lice, you and your dog are not at risk of catching them.
Chewing lice also cannot survive long away from a host. They depend on the warmth and humidity of a cat’s body, so they die relatively quickly once separated from fur. This means environmental contamination is a much smaller concern than it is with fleas, though washing bedding and cleaning grooming tools is still a smart step during treatment.
Why Lice Matter Beyond Itching
Chewing lice can serve as intermediate hosts for a common tapeworm. If a cat swallows an infected louse while grooming (which is almost inevitable), the tapeworm larvae inside it can develop into adult tapeworms in the cat’s intestines. So a lice infestation sometimes comes with a tapeworm problem as well. If your cat has been diagnosed with lice, it’s worth checking for tapeworm segments, which look like small white rice grains near the tail or in the stool.
Telling Lice Apart From Dandruff and Fleas
Lice, dandruff, and flea dirt can all look like tiny specks in a cat’s coat, and it’s easy to confuse them. Here’s how to tell them apart:
- Nits vs. dandruff: Nits are teardrop-shaped, white or yellow, and cemented to individual hairs. They won’t come off with a gentle brush. Dandruff flakes sit loosely on the skin surface and fall away easily. Empty nit casings look more translucent or grayish.
- Lice vs. flea dirt: Flea dirt (flea droppings) appears as dark reddish-brown specks. If you place flea dirt on a damp paper towel, it dissolves into a reddish smear because it’s digested blood. Lice are pale, tan, or yellowish and visibly move if you watch closely.
- Movement: Lice move slowly and stay close to the skin. Fleas jump quickly and are much harder to catch. If you see something small and pale crawling sluggishly through the fur, lice are the likely culprit.
How Lice Are Treated
Several topical treatments effectively kill chewing lice on cats. The most commonly used active ingredients include selamectin, imidacloprid, and fipronil, all available in spot-on formulations applied to the back of the neck. Pyrethrin-based sprays and shampoos also work well against lice. Your vet can recommend the right product based on your cat’s age and health.
The key detail with treatment is timing. No product kills the nits (eggs) already attached to the fur. Those eggs will hatch days to weeks later, producing a new round of nymphs. To break the cycle, treatment needs to be repeated at least once, typically every one to two weeks, to catch newly hatched lice before they mature and lay more eggs. Some infestations require three or four rounds of treatment before they’re fully cleared.
For young kittens who can’t safely receive standard flea and lice products, a diluted lime sulfur solution applied weekly for about four weeks is an effective alternative. It smells unpleasant but is gentle enough for fragile animals.
While treating the cat, wash all bedding in hot water and clean or replace grooming tools. If you have multiple cats, check all of them. Even if only one cat shows symptoms, others in the household may be carrying lice without obvious signs yet. Treating all cats in the home at the same time prevents the infestation from bouncing back and forth between animals.
Recovery and What to Expect
Once treatment begins, itching and irritation typically improve within the first week as adult lice die off. Damaged skin and hair loss take longer to resolve. Scratched or infected skin may need a few weeks to heal fully, and hair regrowth in bald patches can take a month or more. Cats that were heavily infested often look dramatically better within three to four weeks of starting treatment, assuming all follow-up doses are applied on schedule.