[MalcW]

We have a large pot plant in our office which seems to be hoem to a lot of very small black flies. Anything we can do without chucking all of the soil and re-potting it? Thanks.

[mumofstig]

They're fungus gnats aka Sciarid flies
http://www.bbc.co.uk/gardening/advice/pests_and_diseases/identifier.shtml?black_fungus_gnats

some good advice here
http://www.bbc.co.uk/gardening/advice/pests_and_diseases/identifier.shtml?black_fungus_gnats

I found if I only water from the bottom, they don't seem to become a problem 

[MalcW]

Thanks MoS. We'll see what we can do.