so the mineral oil story is true?The BTI briquets will work well as long as they are just larva.
If you have Pupa, you are going to need to use a oil to leave a film becasue pupa do not eat so the BTI will do nothing to kill them, you need to suffocate them.
I work for Mosquito Control in my county and we use a petroleum based additive with basically mineral oil. It dissapates in 24-36hrs, doesn't hurt anything big enough to break the surface tension.
Other than that if you can get your hands on something called Abate. when the ditch drys up if it ever does throw some of that in there ever so many feet and when it floods it will pretreat the ditch and you won't have any mosquitos.
Cool. Do you have to spray it or can you just pour it?