A house cat makes a good mouse/mole deterrent. We have an abandoned cat that adopted us and promptly had several litters. She trained each one of them to be a mouser with great success! Only problem is she likes to bring her catch into the house to show it off, before its dead.
As far as flies go, 2008 was the worst year for flies around here. We used a fly trap years ago called a “Big Stinky” and it worked surprisingly well. Especially if you put a piece of afterbirth inside with the water. It’ll attract flies for acres and kills them dead. Its amazing sometimes how effective it is, but don’t put it near your home as it lives up to its name.
I found it online here:
But our local feed store had an equivalent that worked just as good. The idea is to have an attractant in the water so when a fly enters the top it gets trapped and drowns. After awhile the “bug juice” ferments with fly enzymes and attracts other flies like you wouldn’t believe. Neat thing about it is when the jar fills up, you dump it into the garden since fly cadavers are high in phosphorus and acts as a fertilizer (but save some of the bug juice when you refill the water). ~ M