Here is what I learned that Tuesday night and what completely changed how I understood the problem.
When you see fleas on your pet or jumping across your carpet, you are only seeing about 5% of the total infestation.
The other 95% the eggs, the larvae, and especially something called pupae are invisible.
They're buried deep in carpet fibres. In sofa seams. Under furniture. Between floorboards. In the cracks around skirting boards.
And here is the part that nobody at the pet store ever explains:
Flea pupae are wrapped in a sticky, protective cocoon that no chemical spray, bomb, or topical treatment can penetrate.
Nothing reaches them. Not the prescription treatment. Not the home spray I'd used three times. Not the flea bomb I set off in the living room the week before.
They just sit there. Waiting.
They can wait for up to six months.
Then, the moment they sense heat or vibration a person walking across the room, a pet settling on the sofa they hatch. All at once.
That's not bad luck. That's not me failing to clean hard enough.
That is the flea life cycle doing exactly what it was designed to do.
Every product I'd used killed the adult fleas I could see. The 95% I couldn't see kept rebuilding the infestation from below.
I had been solving the wrong problem for three weeks straight.