Usually mosquitoes in my area start reproducing by end of May, and it’s unlivable by the end of June. I set up the buckets by mid-May, so I guess the answer is: immediately, the whole initial population growth has seemingly been prevented.
The Bti takes 2-3 days to fully dissolve though, and add to that the reproductive cycle of mosquitoes… If you don’t start ahead of the season, I guess you could wait for 2-4 weeks before seeing any drop (which is why I did it preemptively).
Usually mosquitoes in my area start reproducing by end of May, and it’s unlivable by the end of June. I set up the buckets by mid-May, so I guess the answer is: immediately, the whole initial population growth has seemingly been prevented.
The Bti takes 2-3 days to fully dissolve though, and add to that the reproductive cycle of mosquitoes… If you don’t start ahead of the season, I guess you could wait for 2-4 weeks before seeing any drop (which is why I did it preemptively).