onions and garlic

well i'm growing some onions and they are doing well but they have some flys on them, they dont seem to be doing anything bad to them but they wont go away...
what should i do?
also i'm growing some garlic, well it was some left i had in the kitchen & i just planted it but i was wondering does it grow like a onion or does it grow on top of the soil?

is it ok thats they are all in pots? i do have a garden but my dog would eat them lol

thanks