What kind of oil can I use in my rain barrel that will kill mosquito wigglers and not harm the plants I use the water on?
Kill Mosquito Wigglers
Certified GKH Gardening Expert
I would recommend using mosquito discs, available at most lawn and garden centers. Mosquito discs are doughnut-shaped rings that you can float in a pond, birdbath or other water feature (like your rain barrel). They slowly release Bti (Bacillus thuringiensis israelensis), which is a bacteria that kills mosquito larva but is harmless to plants, humans, pets and other wildlife. Bti is a different strain of Bt from that used by gardeners to control the larvae of caterpillars and other garden pests and is effective in controlling mosquito problems. Here is more information on that: https://www.gardeningknowhow.com/plant-problems/pests/pesticides/bti-insecticide-information.htm