Another thing to try around the outside of the house is powered SEVIN. You can buy it many places & it's reasonably priced. In the spring when it's dry out(on a dry day) we sprinkle it next to the foundation & about 6" from the foundation in a wide path. It seems to last for the whole year. We don't use it by our backyard pond. Seems to work MUCH better than sprays.
It's now against the law to sell Diazinon.