flies in the compost

My compost bin is infested with small flies--I think they are fruit flies.
My wife won't open the lid now because it's got so
bad:eek: You need an NBC suit to get near.

I put lime in the bin to try and reduce the acidity but it made no difference.
There are also a lot of slugs in there too.--Is this normal??
Can I do anything to reduce the amount of flies? :confused:

 

Hi scrumpyjack...Mmmm nice name
My bin is just the same and I'm the one who has to put the household waste in because of them.
When it gets really bad I just leave the lid off for a day or two..that's when a Black bird sometimes gets in and has a feed on the bugs and thugs so that helps.

 

This is apparently because kitchen waste is exposed on top. Flies normally go if you just pop some newspaper on after, basically browns always on top of any greens.