If you find a flea on your dog, there's a 95% chance that it's me. Although I do have cousins known as dog fleas, they are rarely found in the United States.
Unlike people, dogs satisfy my every need--I live on them, mate on them, and best of all, I eat them. As soon as I see a tasty looking dog, I jump right on--and I can jump a long way. If you could jump as well as I can, you'd be able to leap over the Empire State Building. You wouldn't survive the landing, of course, so don't try it. I may need you as an alternate food source if your dog manages to scrape me off his body.
I was born on a dog (or, more accurately, laid, since I started out as an egg). Flea eggs aren't sticky, so most of them fall off onto wherever the dog is at the time, his bed, the carpet, the dog park--who cares. I can survive almost anywhere in my pupal stage.
Those of us who were really lucky stayed right on the dog. After a couple of days (in ideal conditions) we gnaw our way out with a chitinous little egg tooth and turn into larvae.
Here I am emerging from my egg:
As long as I stay on the flea infested dog, There'll be plenty of food around--flea poop--nutritious as well as delicious!
And to think you call it "flea dirt!"
A week or so later, I spin a cocoon and become a pupa.
And then I lie in wait!
I can wait for a year or more if necessary. When it's warm and humid or I feel the vibrations or detect the breath of a passing dog, cat, or human, out I come!
The first thing I do within seconds of landing on your dog (or on you if no dog is available) is to eat a good meal of blood. Once I've eaten, I become an "obligate parasite," which in flea terms means "suck blood or die!" The biggest danger to me at that point is that your dog will scratch me off.
I can't reproduce until I've eaten, but as soon as my tummy is full, I go looking for a mate: not a problem on most dogs. We'll have lots of sex and make lots of little baby fleas--up to 50 a day for the several months that I will live. Whoever coined the term "breeding like rabbits" obviously didn't know about fleas.
And some other information about me:
This one is funny: