| There was discussion a few months ago on another board about wasp stings possibly causing a koi death. No conclusion was reached, but it would certainly be best to avoid wasps in the water. Interesting observation on the fish not eating the wasp.
I do not believe there is any pesticide suitable for your purpose. I hope the heron statue is movable (not cemented in place). If so, your best bet is to relocate it at night to a spot where you can use an insectide the next day. If the statue is of the type I am imagining, the opening on the bottom is more like a wide crack on the underside. This makes it difficult to use water, vinegar or other non-poisonous 'remedies' that make the nest site less comfortable. Query: Is the heron in full sun? If so, the metal may become too hot for their liking when summer arrives and they may move on. |