I used to work for a pest control company and this is what we would use for mosquito jobs. We would apply it by using a backpack sprayer similar to something like this, but I'm sure you can find a cheaper backpack or applicator.
As far as if it works, the majority of the customers that I asked about it said that there was a noticeable difference. It's not gonna get rid of 100% of your mosquitos, but it should cut it down quite a bit