We have these tiny (miniscule) grey to black bugs that I don’t think are fleas. They are almost flat and have little tiny antenae. They are located mainly in the bathroom and on the fireplace hearth. I’m not sure if they bite. At first there were a lot of them, now not as many, but there are still some there. I have tried to spray around the house, inside and around the foundation and have washed all the cushions on the couch and sprayed the carpet around the fireplace.
What you are seeing are probably springtails. Springtails are tiny grey insects that have an appendage attached to their abdomens called a furcula. This furcula is held folded underneath the body and when they are disturbed they will release it which springs them into the air. Springtails are always found in association to some kind of moisture problem. They do not bite or damage household items. Sometimes if they get on you, the movement on the skin may cause a light irritation which may be percieved as a bite. They feed on the mildew and fungus which grows in wet environments. You may want to have someone inspect your home for water leaks, plumbing problems, or drainage issues. If you are finding them around the base of the chimney, it is possible that there may be a roof leak around the chimney area. If you have standing water or really wet conditions around the foundation, this could also be a source. They are many times found in bathrooms as they are seeking out sources of moisture. They are frequently found in sinks, tubs, and toilets because they will climb into these areas but cannot get out. They do not live in the drain lines. The only way to get rid of springtails is to find the moisture problem and correct it. Once the area dries up they will go away.