Ear mites are tiny parasites that live in the ear canal, and the irritation they cause is out of proportion to their size. A cat troubled by them focuses attention on the ears with an intensity that is hard to miss once you know the pattern: scratching, shaking and rubbing that keeps returning through the day. The catch is that ear infections and allergies can imitate some of the same behaviour, so the details inside the ear matter.
Scratching and head shaking with a target
The behaviour is strikingly ear-centred. A cat may scratch hard at one or both ears with a back foot, shake her head in short bursts after being stroked or after waking, and rub the side of her head along the floor or furniture. Scratching can be vigorous enough to leave small sores or a bald, scratched patch behind the ear, and some cats flick an ear repeatedly as if something is crawling there, which in a sense it is. Compare this with general itchiness from skin allergies, which spreads across the head, neck and body. Mite irritation stays stubbornly local, and it tends to disturb rest, with cats waking to scratch or shake several times rather than settling.
What the inside of the ear looks like
When a cat allows a gentle look into the outer ear, mite cases classically show dark brown or black debris that is dry and crumbly, often described as resembling coffee grounds. That material is a mix of wax, dried blood and debris from the mites themselves. The ear canal may look red and irritated, and there can be a noticeable musty odour, though a strong yeasty or pus-like discharge points more toward infection. Do not poke cotton buds or instruments down the canal to investigate; the canal turns sharply, is easily damaged, and home digging mostly packs debris deeper. A photograph of the outer ear in good light, plus your description of the debris, gives the vet useful information without risking the ear itself.
Other cats and the household picture
Ear mites pass between animals through close contact, so a key clue is company: a second cat, or a dog in the home, starting to scratch at the ears in the same period strengthens the picture considerably. New arrivals are a common source, including a recently adopted kitten who seemed fine at first. Note which animals are affected, who arrived most recently, and whether anyone sleeps curled up together, because a vet will likely want to examine and treat all in-contact pets rather than just the one scratching loudest. Treating only one cat in a shared home often leads to the problem quietly circling back within weeks.
When an ear needs a veterinary look
Book a vet visit if scratching and head shaking persist beyond a day or two, if you see dark crumbly debris, or if an ear looks red, sore or smelly. A cat who tilts her head to one side, loses balance, cries when an ear is touched or has scratched the skin behind the ear raw needs to be seen promptly. At the clinic the vet can look deep into the canal with the right instrument, confirm what is living or growing there, and choose treatment that is safe for cats. Recording which pets are scratching and when it started in your KinsLe Pet Passport helps the vet treat the whole household picture in one visit.