Nightcrawlers are robust earthworms highly valued for fishing bait and producing nutrient-rich castings, the end product of their digestion. Unlike the smaller, surface-dwelling red wigglers commonly used for composting, the European Nightcrawler is larger, more active, and is the preferred species for farming operations. These worms thrive in specific, cooler environments and, with the right care, can provide a steady supply of both large bait worms and valuable soil amendment. This guide details how to start and maintain a nightcrawler colony.
Establishing the Worm Habitat
Containers require proper airflow and drainage, typically achieved by using a lidded bin with numerous small holes, approximately 1/8-inch in diameter, drilled into the bottom for drainage and into the lid and sides for ventilation. Placing the primary bin over a second, un-drilled tray will catch excess moisture and allow for the collection of liquid fertilizer.
European Nightcrawlers thrive in a cool, stable temperature range, ideally between 59°F and 77°F, with the best activity occurring around 60°F to 70°F. Suitable locations are often temperature-controlled spaces like basements, garages, or heavily shaded outdoor areas. The bedding material should be a mixture of carbon-rich items like shredded cardboard, peat moss, or coconut coir, filled to a depth of four to eight inches. This bedding must be pre-moistened to the consistency of a wrung-out sponge, feeling damp but not releasing water when squeezed.
Feeding and Maintaining the Colony
Nightcrawlers are detritivores, meaning they consume decaying organic matter. Their diet should primarily consist of soft vegetable scraps, non-citrus fruit peels, and grain-based feeds like moistened chicken crumbles. Avoid meat, dairy products, oily foods, and excess salt, as these items decompose poorly and can harm the colony.
Feeding should occur only when the worms have consumed most of the previous offering, typically every five to seven days, as overfeeding leads to a toxic environment. The food should be buried a few inches below the surface of the bedding in a different spot each time. This practice helps deter pests like fruit flies and encourages the worms to tunnel and aerate the substrate. Maintaining the bedding moisture is accomplished by misting with dechlorinated water whenever the surface appears dry.
The colony’s health depends on maintaining a neutral to slightly acidic pH level, ideally between 6.0 and 7.0. Acidity builds up as food scraps decompose, leading to stressed worms. To correct this, a light dusting of crushed eggshells or agricultural lime (calcium carbonate) can be sprinkled over the bedding surface every few weeks, acting as a buffer to raise the pH. This calcium also provides the necessary grit for the worms to properly digest their food.
Harvesting and Troubleshooting
Worms can be collected by exploiting their natural aversion to light. By exposing the bedding surface to a bright light source, the worms will burrow deeper into the substrate, allowing the top layer of bedding and castings to be gently scraped away. Repeating this process concentrates the worms at the bottom of the bin for easy collection. Finished castings can be harvested by simply sifting the material through a screen, which separates the worms and any unconsumed debris.
A common threat is protein poisoning, often visible as a “string of pearls” swelling along the worm’s body. This is caused by an overly acidic environment and the buildup of ammonia from overfeeding or high-acid foods. If this occurs, immediately remove any remaining uneaten food, add a fresh layer of dry bedding, and apply a generous dusting of calcium carbonate to neutralize the acidity. Mite infestations are another problem, usually indicating the bin is too wet or too acidic. To control mites, reduce all water and food inputs and place a piece of melon rind or damp newspaper on the bedding surface to act as a trap, removing it once the mites congregate.