Hi @FlowHive7 ,
Any organics, including what falls down from the hive. Polen, parts of dead bees etc.
Why do you use oil at all? So far WA was quite lucky regarding parasites. The main existing one is wax moth and ants may cause a nuisance. Oil is mainly needed for catching something that falls on the tray to prevent it from going back to the hive. We don’t have varroa of SHB so far, so there is no real need to use oil.
By the way, there is a local Perth group on this forum.