I have diffenbachia (tropic snow) plant in 10 inch pot. I guess I have overwatered my plant becasue there are lots of black flies around and leaves are turning yellow. And I also noticed that there are some type of bugs or warms in the soil. They are gray color and have lots of legs. When I touched them, they curled up. I have asked this question in another form and they said that those things may be sow/pill or potato bugs. I made a searh on the internet and I have found out that they are certanly not those bugs. Those bugs have oval shape but the bugs in my soil are like warms. Dou you know what they are?
Today I repotted my plant and saw there were a lot in the soil and I think they were eating the roots.
Thanks
DERYA

The gray bugs you have sound like "Millipedes" from your description. and yes they can eat the tender roots of plants and even any leaves that may have falling down onto the soils surface.
They can lay their eggs in the soil and you could have hundreds if not more like I did. I choose not change the soil since it was winter when I noticed hundreds of them it seemed. I didn't want to use chemicals, so instead I hand picked them out when they came to the surface at night after the light were off using a flashlight and an old coffee can to put them in, not a pretty site!

With the other black pest, click SEARCH, located on this site at the top top the page, type in "Fungus Gnats" for information on them.