Where you have spotted this black bug with white spots may have a bearing on the definitive answer.
If you have seen it in the Far East, particular China, Japan and Korea, then it is probably the Asian Longhorned beetle, known as the Starry Sky or Sky Beetle, although the species has been accidentally introduced to the United States and is regarded as a pest.
More prevalent in the home is the varied carpet beetle, which is about three millimeter long beetle and as it feeds on natural fibres it can be a serious household pest that damages carpets, furniture and clothing.
