Let’s suppose that there are absolutely no fleas in your home and your cat is a full-time indoor cat and is entirely flea-free. It is the perfect situation for a cat owner concerned with the damnable cat flea.
But outside there are cats and dogs and wild animals. These animals have fleas. The fleas can therefore be in the grass and around the home.
The owner of the flea-free cat goes for a walk on the grass and has a picnic. A couple of fleas, a male and female, jump onto her. One of them bites her foot.
She returns home and makes a cup of tea and watches the tele. The two fleas that are on her, in her clothes, jump off onto the carpet. They wait for 24 hours until the pristine family cat walks by and jump into her fur. The flea can survive for 2 days when off the cat and 115 days living on the cat.
They clamber down to the cat’s skin and bite the skin for blood. After their meal the fleas mate on the cat’s skin. The female lays eggs within 24-48 hours. She can lay up to 2,000 eggs in four months. The eggs fall off the cat onto the carpet and incubate. The eggs hatch in 10 days. The larvae feed on debris. They make a cocoon and enter the pupal stage which lasts days or months. They hatch. They wait for the same cat to come by and jump on. They can wait for up to 1-2 weeks and survive without feeding.
At any given time the cat flea population at home would be 1% adult fleas and the remainder are in the egg, larval and pupal stages. The pristine flea-free home is no long flea-free. That’s how indoor cats get fleas.
Alternatively fleas can get in windows, doors and e.g. cat flaps. And visitors can walk in fleas if their cat has them. I have painted an unpleasant picture and the chances of a indoor cat getting fleas is fairly remote I’d say but it does happen. Personally the only thing I would do is to comb an indoor cat with a flea comb regularly to check for fleas. I would not give any preventative treatments under these circumstances because they are poisonous. Stick to flea combs until you have to step up to something stronger.
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