Posted: 26/09/2014 at 19:17
They come up for air when it is too hot.
Luctong, if the bin is smelly, get a compost stirrer (about £10 on-line) stir the compost up a bit, take a newspaper and separate all the sheets, scrunch them up and put them in and try to stir them in to the compost.
Do this again a few days later.
After about 10 days it should not smell nasty any more.
Are you putting large amounts of grass clippings in all at once? This can cause the bin to become anaerobic/smelly/slimy. The aim is for an aerobic system, so air must be incorporated and you need the balance between greens (nitrogen) and browns (carbon).
So always add scrunched up newspaper in layers with your grass cuttings and other greens.