So we have two fields, one with mostly grass and the other is 100% alfalfa, we have the horses currently on the grass one and they are getting eaten alive along with us every time we go to change water. We have not had Mosquitos this bad in along time. So no matter where you are the Mosquitos are coming make sure to get your west Nile vaccines for your horses and make sure you wear some kind of repellent because when the rain stops they are coming!! When it’s real bad I like to use a old cowboy trick(disclaimer be careful with deet I am not a vet, I do not recommend this for light bugs or flys and always wash off your animals every 24 hours) when it’s real bad like this I use 100% deet I spray it only on the main and tail and never let it touch the skin !! I also spray the brim of my hat and my boots! It really helps but 100%deet is really bad for you so use it sparingl, and carefully! And make sure you vaccinated your babies!!