How to get rid of bugs on Lilly Pilly?

[sper]

 

Hi everyone, I have Lilly pillys in my front and backyard and they have some weired pimples on thier leaves. I can see the black bugs behind those leaves, but not sure what to do.

please advise me some trick or spray that I can use to get rid of those bugs.

please see attached pictures.

 

[sper]

Thank you guys, going to get it asap.