Systemic granules would be easiest, probably.

Have you seen any Wasps in the house?

No, but when the weather was good I did put the plant outside for few hours....could it be that they have eaten it then?

My mistake - I was thinking of bees!
The queen bee chomps leaves up which she chews and then uses to make egg "nests". Not sure if all bee species do this though..........

Wasps do that too, Meanie - they chew up wood or fibrous leaved plants to make their nests.
I'm wondering about vine weevil in the pot - might be worth turning out the plant to see what lurks in there. Or it might just have been some opportunist insect when the plant was outside, if that was recent, and not a permanent resident on the plant or in the pot.

Thank you! :)
It seems like the pot is clean and no one else is living there except my plant, so must have been some opportunist!is there anything I can do to scare the insects away in the future?

Can I suggest you just don't stand it outside any more... it's always risk if you do.

Mu first thought was leaf cutting bees though perhaps they aren't quite neat enough. Vine weevil holes are often more irregular than these

Mice are fond of them...

It was vine weevil I found it sitting on the leaves this morning! Does it mean that there are more of them around?

It could do. The main danger isn't from the leaf damage though, its from the grubs before they hatch out. They sneakily eat the roots of the plant and often the first you know about it is when the plant suddenly keels over and dies.