Blood worms (Lumbricus rubellus) are a species of common earthworm found in many temperate ecosystems. Because they consume a large amount of organic material, they are good at aerating and mixing soil, which is beneficial to your garden. These segmented worms range from about 1 to 4 inches in length and have smooth, reddish skin. They are sometimes called red worms or red wigglers, and not to be confused with Glycera dibranchiata, a midge larva that lives in tidal marshes and goes by the same name. Blood worms are classified as segmented worms, Class Annelida, which includes approximately 9,000 species. Of those, earthworms comprise about 2,500 species. Terrestrial earthworms are classified according to where they live in the soil. Litter dwellers live in the thin layer of decomposing material just below the surface; topsoil dwellers live in the top 6 to 24 inches; and deep burrowers live as much as 6 feet deep. Blood worms are a topsoil-dwelling species, usually living 6 to 12 inches below the surface. As blood worms burrow through the soil, they ingest decaying organic matter. This brings subsoil to the surface and mixes topsoil with organic matter. Called oxygenation or aeration, this process improves the texture and structure of the soil by creating cracks and channels that allow nutrients to enter the soil. This loosens compacted soil, helping plant roots to grow deeper, improving drainage and allowing water to reach plant roots more efficiently. Castings are the organic matter that pass through the blood worms after it completes digestion. Blood worms derive nutrition from decaying plant matter and decomposing remains of animals, leaving behind castings. This process leaves organic matter, beneficial bacteria and enzymes, minerals and cellulose in a form that is accessible to plants, resulting in healthier plants. Blood worms can produce their own weight in castings every 24 hours. To attract blood worms to your garden, provide food sources that encourage them. You can do this by creating a compost pile that includes grass clippings, old newspapers and vegetable and fruit waste. Do not over-water your garden, and avoid over-tilling and using fertilizers high in nitrogen. Worms are more active at room temperature than at cooler temps. The best temperature range for blood worms is 71 to 89 degrees Fahrenheit.- Ryan McVay/Photodisc/Getty Images