I have been using your mosquito control solution for over six weeks now and the results are fantastic. In place of Mosquito Dunks, I ordered Mosquito Bits from Amazon which is the same product in a pellet form and which works better for the small containers of water which I am using. I am growing increasing numbers of my North American Hibiscus in a few inches of standing water so mosquitoes are a real problem. I am using 2íx3í cement mixing tubs. I have been using liquid Bayer Advanced Tree Shrub Protect and Feed (Imidacloprid 1.5%) because I need it to control problems such as whiteflies and found that it quickly kills Mosquito larvae in seconds. Imidacloprid is quickly absorbed in the leaves and stems of Hibiscus and lasts for months but canít be used for many applications because it will kill aquatic organisms. Imidacloprid has been found to be effective against Mosquito larvae but is not recommended because other chemicals have greater efficacy. Imidacloprid is a specific solution which works for Hibiscus but I would not recommend it for other plants without testing.
The Mosquito Bits are now part of my long-term mosquito control solution. In containers with no overflow, the Bacillus thuringiensis Israelensis (BTI) bacteria almost appears to be a self sustaining solution and I have been tempted to see how long a tub could go without a re-treatment but have decided to not take a chance for now, given that my grandchildren are frequent visitors. I regularly check the water for Mosquito larvae but am unable to find any. I sometimes see small swarms of Gnats hovering above the tubs but Gnats donít bite. BTI has been reported to be effective against some species of Gnat larvae. What I donít see in any Mosquito swarms which appear to avoid the tubs.
My ideas for growing hardy Hibiscus in standing water can be found here: