Earthworms are native to Europe and have spread in range to western and central Asia, as well as North America. They typically can be found in two ecophysical areas: above or below the soil. Above-soil earthworms consume decaying vegetable matter. Sub-soil earthworms create either horizontal or vertical burrows.
Horizontal burrowing earthworms generally stay within 1-2 feet of the surface, emerging to the surface at night and during rain. They eat the soil as they move through it, creating a constant, shifting network of burrows. Vertical burrowing earthworms dig one, permanent burrow up to 6-feet deep, returning to the surface periodically to eat plant material.