Mosquito dunk uses the same mechanism as mosquito bits, a bacillus that specifically targets its intended victim. If you've ever used 'dipel' to control caterpillars, it's the same thing, basically (used it since the 70s.)
Do you have an empty pot you could invert and use as a pedestal underneath the schefflera? Elevating it would get it closer to the light and provide a bit more useful cover.
Chamille really likes carrot greens. She's not wild about the turnip greens, radish greens, kale, broccoli or other stuff I'm growing for her so the feeders get to enjoy them.