There are several organically approved pesticides that use natural occurring micro-organisms to kill bugs. This is what I use on my farm. The first is Dipel for caterpillars (Bacillus thuringiensis )and the second is BOTANIGARD®, for small insects (Beauveria bassiana). Both of these organic pesticides rely on micro-organisms to attack specific bugs and are inert to everything else. They are approved for use up to day of consumption as the active ingredients only harm bugs, not humans.Please research them!
These will NOT harm fish if there is enough over-spray to get into the water.
I have had a problem with cabbage worms lately. They eat my lettuce as I have no cabbage. I have been looking for worm droppings and then I look for the worm and kill it. If you have a lot of systems this is a problem. I have also started growing marigolds amongst the lettuce. The plants got huge and are starting to bloom.. I have had a lot less problems with the worms. I plan to build a cover like Chris has in Kona. I have already bought the mosquito netting to cover the troughs with. Mahalo Chris for your great pictures. I now know how to build the cover to the troughs.. Another bug I have encountered lately which brought back childhood memories. I don't know its scientific name but as a kid we called them tomato worms. They are as big as a cigar and have what looks like a tail. I realized I should have taken a picture. I have had a few aphids. I just rub them off. On my citrus trees in the ground I use water with soap and olive oil but I wasn't sure what effect the soap would have on the fish. If I find a badly affected plant I will move it to a hospital tank until I rid it of the aphids. Chris is right about the biological pesticides. I used Dipel for year for my dirt gardens. It shouldn't bother the fish at all. Chris where do you find these products in Hawaii. Since I moved back in 98 I have looked for them but It is difficult to find them.
I'll say to be careful with neem oil (well most any oil actually) around an AP system since oils can cause difficulties in respiration for fish if the oil coats their gills.