I have recently tried adding urine (diluted with 2 parts of water) to my plastic compost bin and it has gone mad. every time I lift the lid a warm fug hits me and when i stir in new veg waste, the thing is crawling with worms - tiger worms by the look of them, but where did they come from, and can I transfer them to a wormery so that I save the £20.00 that they expect you to pay.