HELP!!!!!!!!!!!! LITTLE WHITE BUGS HELP!!!!!!!!!!!

I have a 75 gallon fish only set up with no live rock and out of knowhere this morning when I turned on the lights there were hundreds of little white bugs crawling on the inside of the glass. But they seem to disipear the longer that the lights are on. Does anyone know what these are? Can these be harmful to my fish. I have 3 damsels that are cycling my tank and they seem to be doing fine. But will they be affected by these bugs? Is there any way to get rid of them? I don't know what to do! PLEASE HELP!!!!!!!!!!!!!