Doesn't matter if the insects were aphids, spider mites, whiteflies, or thrips... just doesn't matter. I've found neem oil to be pretty ineffectual, personally... rather, I have two products that are always on my shelves - the first is Dr. Zymes Eliminator (if you can't get that where you live, look for some Spinosad). This will kill any of these insects - they suck on the leaves as opposed to eating them.
The second thing I always have on hand is BT (bascillius thuringiensis) which will kill things that actually chew on the leaves - things like catepillars...
Both are organic, both can be used no matter what stage your plant is in - right up to the day of harvest - and both will kill adults, eggs and larvae .. The only other thing I use is Mosquito Bits for fungus gnats...
For your next grow, be very aware of any little mark on your leaves... if it's not something like a calcium deficiency, it's probably an insect and you don't need to actually SEE the damned thing to start protecting your plant... but always spray these or anything just before lights out.
Good luck...