I have a, Euonymus japonicus.flowers, that has, for the past few years been attracting swarms of flies. Is there any solution to this other than cutting it down. I want to keep it as it has grown into an attractive small tree. p.s. The tree is over a koi pond, and I cannot use spays.

Some plants are pollinated by flies instead of the more attractive bees and butterflies. Hey, a butterfly bush might work there, they grow pretty fast. You could try adding extra nitrogen in your fertilizer, this will give more green vegetative growth and less flowers, or you could try shearing it like a hedge when the flowers start to appear