Earthworms tend to burrow deeper into the soil during winters where the temperature is warmer. They do this to escape the harsh conditions of the surface, which usually turn cold, snowy and dry during winters. As they burrow deep into the soil, they feed on organic debris, making tunnels as they move along. The earthworms also expel worm castings, enriching the soil in the process. They slow down their metabolic rate and become less active to conserve energy, but they do not hibernate.