You can download my scene and layered Photoshop files form that link (please do not use them for commercial purpose) I am try to share my workflow. I hope u can check and help to understand and improve our Octane knowledge. Please share your results.

 

https://drive.google.com/…/0B2JFW0aq6XuqVG8wN1hWOGcxZ…/view…

 

I download Beetle model from http://animium.com/
HDRI image from SachForm Technology 
I did all leaves with Ivy Grover