there are 2 different types of neem oil... one is simply stripped of the active ingredient, "Azerdirachtin" (or close enough for a google search)
even then impotent version, i'd be hesitant to use it on the plant. try to hit just the leaves / underside of leaves as best you can?
if it has the active ingredient, azerdirachtin, ???. -- looks like it degrades after 100 hours of light and water. (wiki)
the limitations in flower pose a problem... weight cost / benefits and someties you gotta toss something on it you'd ather not. Use something that breaks down quiclkly,. pyrethrins supposedly break down in 2-3 days... but that's a contact killer. no residual effect, so it would only be useful in conjunction with a more complete way of killing them.
make sure you knwo what you are dealing with.. if they lay eggs in soil, bti will be safest way to go. that has been used on our food for many generations at this point. you may endure some more damage, but it'll control them within 2-3 weeks... put out traps maybe a little pyrethrin misting to kill some adults.