ok we fog our farm yard due to all the construction we do in it in summer and like to drink our tea on the deck by the pond without donating blood.
I always fog our yard, used to do it with straight malethion but that just didn't work good enough.
My friend suggested using mathador.
Its probably not recommended but it works flawless can't find a living mosquito in the yard after I fogged.
1 Fog usually lasts ~2 weeks max than you hit the point where they start to bother you again in the evenings.