Hi again.
First of all thanks to everyone on this forum who helped me with my Meyer lemon and now finally i have few flower buds only on extreme lower branche and some growth sign on middle branches after waiting 2 months while keeping eye on it several times a day :)

But there are tiny black dots on back side of the leaves on lower part of the plant. I i found couple of flying ants, flying around but not seen any sitting on plant.
I found 1 silky thread probably of spider, which was laddering from soil to lower tiny branch of tree. Pics are added and please diagnose it. Recommend any good pesticide which is available online :)