Little White Bugs in Greenhouse

I know I've read about this on here but I've just scanned all the threads and I can't see it

Anyhoos, on my plants in the greenhouse (its one of the plastic ones) there are little white bugs

no more than 2-3mm long - on the soil surface itself

what do I do about them? if anything

thanks

 

any chance of a pic of them?
if they're whiteflies they can be controlled with this nematode
http://www.harrodhorticultural.com/HarrodSite/product/Pest%20Control_Biological%20Pest%20Control/GPC-510.htm

hope this has been at least of some interest!
good luck

 

Ialways have marigolds in my greenhouse supposed to keep white fly at bay old gardener told me :rolleyes: but they do work (but not on those b****Y ants)