fermentation. Lots of fruit will do it for sure. Shouldn't be a huge issue if it's not a huge area (you haven't tossed in 10lbs of pears for example) and you've plenty of other material the worms can stay in. They'll just keep away until it's finished.

If you know where it's coming from, you can aways take some cardboard pieces and mix it into what is smelling. Just whatever you do don't mix the bin in general and spread that fermentated stuff all over. But some more aeration into what is fermenting will help it stop, and will also take away any toxic gases (any alchohol will evaporate). Fermentation is a anaerobic process, so in future you might want to add more cardboard to keep air flowing when you add a similar feeding next time.

I gave alot of banana peels on sunday/ The worms are all over the banana peels but so are the red mites (I hate the red mites). Wish they would go away for good.