Hi,

I have on my plant plenty of these capsules.
When I remove them, I can see that there is white powder inside.
See red circles in photo attached.

Anyone any idea what that is?
And how to get rid off it?

Thanks!
Clemens

I'm curious, too.

I can't see them very clearly, and I don't know what the plant is to get an idea of relative size, but they look like they could be scale insects. Scale insects come in different shapes and colours and if that's what it is I don't know which one it could be in your part of the world, so these pictures are just examples:

https://www.google.ca/search?q...:

hmmm...could be.
I sometimes see this insect crawling around this plant:

http://bugguide.net/node/view/...

and actually the leaves have a shiny sticky, transparent film now.
Not sure what to do..I just keep spraying insecticide

Possibly some kind of galls which are often caused by insects and mites.

oh...and the size of these capsules is 2mm.

ayuyo said:hmmm...could be.
I sometimes see this insect crawling around this plant:

http://bugguide.net/node/view/...

and actually the leaves have a shiny sticky, transparent film now.
Not sure what to do..I just keep spraying insecticide

Soft scale insects create "honeydew", which is a sticky substance, so if you're seeing mobile stages as in the Bugguide picture you linked to then it does sound like the round things could also be scale insects.