The mixing directions for Neem Oil recommend the addition of a wetting agent, and for that I use a full dose of Safer's Insecticidal Soap. This combo is my favorite general-purpose bug spray. In a good hand-held pump bottle it can take down a yellow jacket in flight. I've used it on daylilies for aphids and red spider mites, but I've never noticed any damage to the plants. A few of them had a really bad case of mites, so after spraying the underside of the leaves, I wiped them with a cloth dampened with the solution.
I used it on some rusty seedlings this spring, but it appeared to have no effect.
