I'm also concerned that a soap treatment might adversely affect the hummingbirds. Someone suggested a sugar solution would cause the flies to stick to the plant-- and that wouldn't seem to be a problem for the hummingbirds-- a better option than soap? I've used Dr. Bronner's peppermint soap on my apricot tree for aphids in the past with some success, but hesitate to use it at this point since I do have a few hummingbirds at feeders in the area now...
I'm also concerned that a soap treatment might adversely affect the hummingbirds. Someone suggested a sugar solution would cause the flies to stick to the plant-- and that wouldn't seem to be a problem for the hummingbirds-- a better option than soap? I've used Dr. Bronner's peppermint soap on my apricot tree for aphids in the past with some success, but hesitate to use it at this point since I do have a few hummingbirds at feeders in the area now...