Oregon State University Extension Service

My pond has become a fly nursery. How can I get rid of them?


Well, the good news is they are an indicator of good water quality and are a great food for your koi. The down-side is that control is pretty limited aside from physical removal as you have done. There are products containing Bacillus thuringiensis var. israelensis that are used for aquatic fly control. I would suggest asking a local pond supply store for fly control products that are safe for koi ponds.

Source URL: https://extension.oregonstate.edu/outdoors-environments/fish/my-pond-has-become-fly-nursery-how-can-i-get-rid-them