Due to this being quite a vague description there is no limit to what these creatures or insects could be. Many species such as this exist in a number of places and it very much depends on what location you are talking about, where they are being discovered and how many you are finding.
The fact that you don't mention whether these worms are found inside the house or in the garden makes it a little more complicated. From the description of a small white worm with a black spot on it, this sounds very much like the larvae of a drain fly. Often drain flies and their eggs can be found around areas where moisture gathers, notably near drain covers, sinks and showers or bath tubs. The flies will lay their eggs in these warm and wet places, they will hatch and then these worms will eventually turn into flies. Some people notice these worms coming through cracks in tiles around sinks and basins or in the areas between bathroom or kitchen tiles.
Although mostly harmless to human beings, most people do not wish to have these insects in their house, so it is advised that you keep all areas around drains, kitchen sinks and showers clean and dry. Also make sure all gaps and cracks in walls and tiles are sealed. If the problem persists it may well be worth calling on the services of a local pest controller. Here is a link to what these insects might be from your description www.ohioline.osu.edu/hyg-fact/2000/2071.html.
The fact that you don't mention whether these worms are found inside the house or in the garden makes it a little more complicated. From the description of a small white worm with a black spot on it, this sounds very much like the larvae of a drain fly. Often drain flies and their eggs can be found around areas where moisture gathers, notably near drain covers, sinks and showers or bath tubs. The flies will lay their eggs in these warm and wet places, they will hatch and then these worms will eventually turn into flies. Some people notice these worms coming through cracks in tiles around sinks and basins or in the areas between bathroom or kitchen tiles.
Although mostly harmless to human beings, most people do not wish to have these insects in their house, so it is advised that you keep all areas around drains, kitchen sinks and showers clean and dry. Also make sure all gaps and cracks in walls and tiles are sealed. If the problem persists it may well be worth calling on the services of a local pest controller. Here is a link to what these insects might be from your description www.ohioline.osu.edu/hyg-fact/2000/2071.html.