Lumbricus terrestris is a large, reddish worm species widely distributed around the world. In some areas where it is an introduced species, some people consider it a serious pest for outcompeting native worms. It has an unusual habit of copulating on the surface at night, which makes it more visible than most other earthworms. Through much of Europe, it is the largest naturally occurring species of earthworm, typically reaching 20–25 cm in length when extended.
Common names
Because it is widely known, Lumbricus goes under a variety of common names. In Britain, it is primarily called the common earthworm or lob worm. In North America, the term nightcrawler is also used. In Canada, it is also called the dew worm, or "Grandaddy Earthworm". In several Germanic languages, it is called variants of "rain worm", for example in GermanGemeiner Regenwurm or in DanishStor regnorm. In the rest of the world, many references are just to the scientific name, though with occasional reference to the above names. Although this is not the most abundant earthworm, even in its native range, it is a very conspicuous and familiar earthworm species in garden and agricultural soils of the temperate zone, and is frequently seen on the surface, unlike most other earthworms. It is also used as the example earthworm for millions of biology students around the world, even in areas where the species does not exist. However, 'earthworm' can be a source of confusion, since in most of the world, other species are more typical. For example, through much of the unirrigated temperate areas of the world, the "common earthworm" is actually Aporrectodeatrapezoides, which in those areas is a similar size and dark color to L. terrestris.
Biology
L. terrestris is an worm. That is, it forms temporary deep burrows and comes to the surface to feed, as opposed to burrowing through the soil for its food as most other earthworms do. An unusual habit of this species is to pull leaves into the mouth of its burrow where they partially decay before being eaten. While they generally feed on plant material, they have been observed feeding on dead insects and feces. The natural lifespan of L. terrestris is unknown, though individuals have lived for six years in captivity. In parts of Europe, notably the Atlantic fringe of northwestern Europe, it is now locally endangered due to predation by the New Zealand flatworm and the Australian flatworm, two predatory flatworms accidentally introduced from New Zealand and Australia. These predators are very efficient earthworm eaters, being able to survive for lengthy periods with no food, so still persist even when their prey has dropped to unsustainably low populations. In some areas, this is having a seriously adverse effect on the soil structure and quality. The soil aeration and organic material mixing previously done by the earthworms has ceased in some areas.
L. terrestris is considered invasive in the north central United States. It does not do well in tilled fields because of pesticide exposure, physical injuries from farm equipment and a lack of nutrients. It thrives in fence rows and woodlots and can lead to reductions in native herbaceous and tree regrowth.
