Not all earthworms are suitable for composting such as the worms that are found while digging in the garden. The worms that are widely use as composting earthworms are:
a) Dendrobaena (Eisenia Hortensis), also known as the European Nightcrawler. This is the largest of the composting worms. These type of worms eat a lot and can produce worm casting in the same proportion of what they eat. The Nightcrawler love damp conditions and able to tolerate and adapt to acid soils better than other worms. But its rate of reproduction is lower and thus limiting its use.
b) Eisenia Fetida, also known as the Red Wiggler or Brandling Worm
Smaller than the Nightcrawler above, these type of earthworms belong to the humus formers group. This group dwell on the surface and feed on nearly 90% organic materials. They are generally darker in colour, and are also called epigeic or detritivorous earthworms.
They are from redworm species normally evolved in natural habitat of leaves, manure, compost piles and other decaying organic waste. These earthworms are voracious eaters in that they are able to process large amount of waste.
They also reproduce well and are prolific breeders. This is why these worms that are generally recommended for vermicomposting. The red wiggler also able to withstand weather and temperature variations.
c) Lumbricus rubellus
This is another redworm species which belongs to the humus feeders group. They like to burrow themself deeper in the soil than Eisenia fetida. These worms are useful in both compost preparation as well as making the soil porous. Generally the burrowers help in mixing and distributing humus through the soil.
It has been proven that earthworms can degrade organic wastes speedily and efficiently. However, to increase the efficiency of vermicomposting, care should be taken to see that worms thrive well on organic matter, and breed faster, adapting to moisture and climatic fluctuations.
The most beneficial feature of vermicomposting is that it eliminates foul smell of decaying organic wastes, as it is a fully aerobic system. It disperse the smell of fresh garden smell.