Hi My names Ezra

Just posting because I'm a new bonsai grower and after having watered my Serissa fodecia i noticed some small white insects around the root. (picture - but its hard to notice)
I've had my bonsai for a couple of weeks now and this is the first time I've noticed them. (I chose to bottom water my tree for the first time too)
I'm not too sure what the insects are and whether or not to just use a store bought insecticide spray?
I've heard that over watering could lead to fungal infections and this could lead to the presents of insects but i don't believe this is the case - as i try and ensure the tree is in need of water before starting to water it.

Any help would be useful
Thanks
Ezra