In our house they seem to jump on me first.
As soon as I notice one, the whole house gets flea bombed and then again a few days later.
I close up the house, lock the cat door after making sure they are outside, turn off the HRV and then let off one in each room of the house and go to work.
I repeat the process 2 days later.
I didnt need to do it last couple of years and we had heaps of flies as per normal in a hawkes bay summer.
But this year I flea bombed in december and immediately noticed a major decrease in flies.
The cats get their flea thing from the supermarket put on the back of their necks every 8 weeks so i was surprised to see some fleas this year.