Getting started part 3 Worms- what type

What kind of worms will I put in my wormery?

Obviously composting with worms needs worms. But what kind of worms? Can you go out in the garden at night, pour water on the lawn and wait for some worms to come up? Unfortunately no. These are earth worms, which live in burrows and just come to the surface to feed. Although they also feed on decaying matter, and would survive for a while in a compost bin, they will not be able to build stable tunnels and will eventually die.

What you need are composting worms-(or epigeic worms to give them their true title) and if you want to go looking for them, the best place to find them- surprise surprise, is in a compost heap (or any relatively thick layer of decomposing organic matter like a mature dung heap)
The worms most commonly used in European worm composting are also known as manure worms- and they are Eisenia foetida and Esenia andrei. The two species are very hard to distinguish, and the names are often used interchangeably. They are also known as Tiger worms, brandling worms or red wrigglers. A mature worm typically weighs between 500mg and a gram with most on the lower side of this range. You will find a healthy population of these in any mature manure heap. Tiger worms are very resilient, breed fast, and in ideal conditions, are capable of 'processing' up to their weight in waste every day and doubling their total mass every three months. They tend to seek out the warmer, most biologically active part of a composting system where they breed and feed the fastest.

Another worm commonly used for worm composting is Eisenia Hortensis, otherwise known as european night crawler, belgian nightcrawler, or 'blue nosed' worm ( a trademarked name). They used to be known as Dendrobaena Veneta until they were reclassified a number of years ago.
Eisenia Hortensis is larger than E. foetida, and can reach 2g in weight. It doesn't breed as fast, but is still capable of increasing in biomass fast in a good worm bed. E hortensis likes the cooler parts of a compost bed, and will remain more active at lower temperatures. In lower temperatures although it doesn't breed fast, a 'squirm' of E Hortensis will put on more biomass than E.foetida as each individual worm will grow strong and tough in colder weather, as long as they are not overcrowded. One of the reasons it has become more popular, is that is a very good sport fishing worm, meaning that breeders can command high prices for small quantities of worms, whereas worms sold for composting only, need to be sold in batches of a minimum of 500g. It is also easier to manipulate the size of E Hortensis by lowering bed temperature and reducing population density to produce large worms for fishing.

It is common to find a mixture of worm species in the healthiest composting systems, especially outdoor ones. Either by design- you put in a mixture to make the most of the advantages of each type or because worms are good at wriggling through the smallest of spaces. If there's a ready supply of food in a container protected from the elements and predators, they'll follow their instincts and move in.

I use a mixture of worms in all my worm composting containers and beds and it has worked well for me. In summer E Foetida tend to be the most noticeable, but as the weather cools, or if a bin gets very wet, E Hortensis will predominate.