Flies in/around compost bin?

Not big bliebottles or anything, just loads of little tiny flies. Is this normal and will it get worse in summer? Due to lack of space the bin is under our back room window. Apart from card, fabric, eggshells and teabags, only raw plant material has gone in it.

 

i think its normal, I have them around mine too. I've been told they are fruit flies. in fact, just googled and found this, its tell you about them and what to do about them.

http://www.recyclenow.com/home_composting/useful_info/compost_bin.html

 

I also have these tiny little fruit flies in my bin - thousands of them !! I had a look at the link Glen provided - it says to keep the top covered or put on some cardboard to stop them laying eggs ... but they are also up the walls of the compost bin - they only appeared when the weather warmed up - but many more than last year ..... Val

 

Thanks for the link glenw. Seems to imply they're not a great thing doesn't it? I put stuff straight into a worktop caddy lined with a bag then put the full bag into the compost bin.
Mine are all up the sides too ismeval. They're like little tiny moths with white wings. I might try leaving the lid off?