The Effect of Blood Worms on Garden Soil

What They Are

• Easily recognizable from their iridescent, maroon or reddish backs and yellowish bellies, blood worms are an endogeic earthworm species, which means they spend most of their lives in the soil's upper 3 inches, creating networks of horizontal burrows. Unlike nightcrawlers and other deeply burrowing anecic worms, blood worms seldom surface. At 2 1/2 to 6 inches long, however, they're easy to find with a bit of digging.

What They Eat

• Endogeic worms such as blood worms are the only worm species that actually eat soil. Nightcrawlers speed leaf litter decomposition and build soil by dragging leaves from the soil's surface into their burrows. Burrowing blood worms, on the other hand, consume soil that already contains large amounts of plant or animal materials in the early stages of decay.

How They Help

• Burrowing blood worms till the soil, increasing its aeration as they consume and digest organic matter. They loosen compacted soil by pushing its particles to the sides of their burrows and binding them with mucus secretions into larger clumps. Their networks of tunnels improve soil drainage over a large area; several million earthworms may inhabit a single acre of soil, notes Marin Rose Society rosarian Nanette Londaree. Blood worms' greatest contribution to soil health, however, comes from their waste. Composed of soil aggregates called castings, they add nitrogen-fixing bacteria to the soil. The pH-neutral, mineral-rich waste also balances the soil’s water, air and solid concentrations to optimize plant growth.

Keeping Them Happy

• Blood worms gravitate to organically rich, moist soils. Take advantage of their dietary needs to attract and keep them in your garden by amending it with compost, leaf litter or other organic material. Loosen the top 3 or 4 inches of soil, add a 3- to 4-inch layer of your amendment and thoroughly work the two. Water constitutes about 80 percent of a blood worm's weight, and each worm loses about 15 percent of its moisture each day, according to Nanette Londaree. Keep the amended soil consistently moist and protected with a layer of wood chips or other moisture-retaining organic mulch.

Summer Siesta

• If the blood worms seem to have vacated your garden soil during summer, don't panic. These workhorses are happiest in soils with temperatures between 50 and 60 degrees Fahrenheit, reports the Penn State Extension. If things become too dry or hot, they simply burrow deeper into the earth, curl up in mucus-lined holes and enter a state of semi-hibernation until conditions improve.