Composting With European Nightcrawlers

“Need information on the European nightcrawler, and how to build a home for up to twenty five pounds of worms.” ~ Jeff Hacker

Hi Jeff,

The European Nightcrawler (also known as the Belgian Nightcrawler) is a worm that has gained a lot of popularity in North America over the years. Like its close relative the Red Wiggler (Eisenia fetida), the ‘Euro’ can be used to process organic wastes (although some would argue not quite as efficiently), but it is a larger-bodied worm – therefore better suited (than E. fetida) for use as a bait worm.

As such, most of the interest comes from those in the bait industry (and those aspiring to be bait farmers). Unlike the Canadian Nightcrawler (aka Dew Worm) – the most popular bait worm in North America – Euros are much more tolerant of warm conditions and tend to fit on the hook better since they are somewhat smaller in size.

There are currently two widely used (and acceptable) scientific names for this species – Eisenia hortensis and Dendrobaena veneta (the former name being the newer of the two). In Europe (particularly UK), the D. veneta name seems to be used almost exclusively, while E. hortensis tends to be used more in North America.

Although relatively easy to raise, Eisenia hortensis seems to have a rather low reproductive rate and slow maturation according to the academic literature (Edwards, 1988; Viljoen et al., 1992 – among others). In general it is thought to be somewhat less effective for use in waste management applications than some of the other composting worms.

It seems some worm farmers disagree with the academic findings, claiming E. hortensis has comparable reproduction and maturation rates to that of E. fetida. In an interesting Worm Digest article (cited below), Kelly Slocum discusses this disconnect between the scientific research and some of the claims made by worm farmers.

She suggests that part of the reason stems from the fact that many farmers likely have mixed cultures of these two species – which generally leads to a far greater abundance of E. fetida over time.

As such, it is recommended that you buy your European Nightcrawlers only from highly reputable dealers, and if you are planning to sell them yourself be sure not to mix them with E. fetida.

On to your next part of your question…

Many people recommend using the “1lb per sq ft of bin surface area” formula when deciding how many worms to add to a system, or (as in your case) deciding how big to build a bin for a given quantity of worms. If we were to use this formula, a bin approximately 8.5 x 3ft (or 6.25 x 4ft etc) with a depth of 2 to 3 ft would do the job.

I personally prefer to let my worm population grow into a system, and thus would actually recommend a stocking density of 1/2 lb per sq ft or even less (if you are patient enough). It almost always takes some time for worms to get used to a new system so it’s better to give them a little more space initially. If conditions are ideal the population will then expand rapidly to take advantage of the available resources.

As I’ve mentioned in other newsletters, it also really helps if you get the bin ready for the arrival of your worms before adding them. Mix in ample amounts of aged manure or food scraps with your bedding, add some water and let the system sit for a good week or two. This way there will be a very well established microbial community (food for the worms) and moisture levels should be well balanced throughout the bin.

Unfortunately, getting into the specifics of actually building a worm bin is beyond the scope of this response, but you should be able to find plenty of info online.

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