Red Wigglers (Eisenia fetida) and Nightcrawlers are fundamentally different organisms with incompatible needs. Nightcrawlers typically refer to the larger European Nightcrawler (Eisenia hortensis) or the deep-burrowing Canadian Nightcrawler (Lumbricus terrestris). Attempting to house these species together in a single system, especially a standard composting bin, will almost certainly lead to the failure of the Nightcrawler population and a less efficient system overall.
Distinct Biological Needs of Both Worm Species
The core incompatibility between these worms stems from their natural ecological roles, which dictate their habitat, diet, and temperature requirements. Red Wigglers are classified as epigeic worms, meaning they are surface dwellers that live and feed in the top few inches of decaying organic matter. They thrive in active composting environments where their diet consists entirely of decomposing kitchen scraps and other carbon-rich materials. Their optimal temperature range is relatively warm, ideally between 55°F and 77°F (13°C and 25°C).
Nightcrawlers, in contrast, often fall into the anecic or endogeic categories, meaning they are deep-burrowing species. The European Nightcrawler (E. hortensis) is larger and tolerant of cooler, more stable temperatures, while the Canadian Nightcrawler (L. terrestris) requires deep, mineral-rich soil and cool conditions. These deeper dwellers are less efficient at consuming the high volumes of fresh, rapidly decaying organic matter that Red Wigglers specialize in. They need a cooler, more stable environment and a diet that includes more soil and mineral content than a standard composting setup provides.
The Outcome of Co-Habitation
Forcing these two species into the same composting bin creates a competitive environment that favors the Red Wiggler. A typical vermicomposting bin is shallow, warm, and filled with highly processed food scraps, which perfectly suits the surface-feeding, fast-reproducing Red Wiggler. The Wigglers are more efficient and aggressive feeders in this environment, quickly out-competing the larger, slower-reproducing Nightcrawlers for food resources.
The warm, high-organic environment of a Red Wiggler bin is biologically stressful, if not lethal, to deep-dwelling Nightcrawlers, which require stable, cool temperatures. Nightcrawlers will attempt to escape the unfavorable conditions, often resulting in “fugue” behavior where they crawl out of the bin and perish. Even if a Nightcrawler manages to survive and reproduce, the Red Wiggler population will explode due to its much faster reproduction rate, quickly dominating the limited space and resources.
Maintaining Separate Environments for Successful Vermiculture
To successfully manage both species, you must maintain separate, specialized environments that cater to each worm’s unique biological needs. Red Wigglers thrive in standard, shallow composting systems, such as plastic totes or flow-through bins, where the focus is on maximizing surface area for processing organic waste. Their bedding should consist of carbon-rich materials like shredded cardboard, coconut coir, or peat moss, which are kept consistently moist and warm.
Nightcrawlers, particularly those intended for bait or soil aeration, require a much deeper container filled with a mix of soil and peat moss. This depth allows for burrowing and temperature regulation. This deeper bin should be kept in a cooler location, such as a basement or garage floor, to ensure the stable, lower temperatures they need to survive and thrive. Successful vermiculture depends on recognizing that these worms serve different purposes and providing each with their own specialized habitat.