Fleas are what brought me to Fluther in 2007. I had a newborn baby and fleas in the house, from the cats. I was googling all about fleas, flea life cycle, how to get rid of fleas, everything, and Fluther had a flea question on the second page of google. I became quite the flea expert, and I tried many things to get rid of them, including a flea bomb and staying overnight in a hotel with the baby, and nothing worked. I ended up hiring a professional (and ripping up the carpeting which they said I didn’t have to do, but I didn’t want the baby to crawl, eventually when she would crawl, on the carpet if it had been treated with pesticide). About three or four years later I had fleas on the deck, and I had to get a friend who worked with an exterminator to get the stuff and spray the deck.
Believe me, after the first go-round with the fleas in the house, I learned that you need a pro.
When you have fleas in the house, they’d need to spray the yard, too.
In your case, you need the pro to spray the yard which will kill the fleas, and then when it rains, the flea stuff will wash away and the kids can go on the lawn. The first time I had fleas, I got a contract with the exterminating company, and they would come as often as necessary within a year. I recommend, for you, to get the contract.
If your neighbor has dogs that have fleas, you can’t stop the fleas from coming over. They’re very tiny and they jump very far (you can google it and learn all about how they hitch a ride, how their goal is to get onto a host, etc.). Believe me, when you learn about them, you realize how they’re just made to survive all kinds of adverse things, like the weather (read about how they survive the winter).