Red Wiggler vs European Nightcrawler for Composting

While the red wiggler is well researched and widely used for composting, another surface worm is creeping up in online conversations about vermicomposting. The European nightcrawler (ENC) or Euro seems to have enough to say for itself to be used as a great composting and bait worm for fishing.

As it turns out you might even have already a mix of both in your worm bin.

This article looks at how to tell them apart, their suitability for composting and their reproduction. 

Eisenia Fetida and Eisenia Hortensis (Dendrobaena Veneta) – Huh?

Let’s clear up some confusion about the name. Earthworms are very common throughout the world and  more often than not there are different local names describing the same worm. Since earthworms have many similarities this can be quite confusing. A red worm in the US might be different from the one found somewhere in Europe.  

The safest bet is to use the scientific names. Unfortunately, the taxonomy for earthworms had a couple of updates fairly recently even within the lifetime of the internet, so there are webpages and posts that are not necessarily updated and still might use the previous names. Add to that the local preferences and you can see how disorienting this can be. 

According to the latest taxonomy update, Eisenia fetida is current and correct, the spelling foetida is outdated, red wiggler is the commonly used name for the same compost worm.

Likewise Eisenia hortensis is the Latin and European Nightcrawler one of the common names for the same compost worm. Dendrobaena veneta is the previous Latin name and still widely used, especially in Europe but actually now outdated.

What is in the name you might ask.

Eisenia fetida – As you would guess ‘fetida’ means foul-smelling or stinking. According to Wikipedia this worm ‘exudes a pungent liquid’ when handled roughly, thus the specific name foetida meaning “foul-smelling”. Presumably this is a defense mechanism against predators.

You could also associate the name with the smelly places where Eisenia fetida likes to hang out like heaps of horse manure.  

Eisenia hortensis – Hortensis is Latin for belonging in the garden, referring to where this worm is most  commonly found. Eisenia hortensis is widely spread in Europe, from Iceland to Ireland to Greece.

How can you tell the red wiggler apart from the euro?

Colour, Shape and Size red wiggler vs european nightcrawler vary at all stages with their habitat, food and stage in life cycle.
Both worms come in variations of colours of the body and the clitellum which can make it hard to determine a single worm. However, when looking at many worms the defining characteristics become more apparent

Red WigglerEuropean Nightcrawler
Colour
Ranges from pinkish brown to darker, reddish brown (think uncooked beef or game – apologies if you are vegetarian)

The older the worm the more pronounced is the stripey pattern which gave it the common name Tiger worm. When contracted, the darker stripes appear wider than and separated by the yellowish stripes. When the worm stretches those yellowy bands seem to be wider than the darker ones, especially towards the tail end

Mature worms have a clearly visible clitellum which looks like a saddle bulging out not far from the head. The clitellum too can vary in colour from brown to yellowish to almost opaque white.

The tip of tail tends to be cream-yellowish even when the hatchlings are only a few weeks old – that way you can tell whether it’s crawling backwards or forwards

Underside tends to be uniform pink greyish for most of the length followed by a more yellow tail
Colour varies. Overall it tends towards a darker, purple to olive brown colour
Stripey pattern similar to the red wiggler (making it hard to distinguish the two just on colour and pattern)
Underside is more uniform pal, blue- pinkish colour head to tail

Clitellum – similar to red wiggler
Size and shape
Weight: ca 0.6 g (average of 10 big ones from breeder bin)
Length: up to 12cm, about 4 to 5 mm in diameter – although a study had found that they kept on growing in the …days while they were observed in a lab;
NOTE: Size also depends on food and density (how many worms per area). I feed worms in my breeder bin on sheep and horse manure and they look bigger than all the worms I have in my stackable worm bin which mostly get kitchen scraps and cardboard. 
Shape: It’s not easy to find differences between the two. If you observe closely you’ll see the red wiggler’s tail tends to be quite flat when crawling (especially after it has pooped when just picked up)
Weight: ca 1.6 g (average of 10 big ones from breeder bin)
Length: up to 15cm, 5-6 mm in diameter

Shape: next to the red wiggler the euro looks like a bodyguard on steroids. After a few months it has clearly outgrown the red wiggler. When stretching the tail doesn’t stretch as much, always staying in a more rounded shape.
Ideal and tolerable temperatures
Red wigglers are surface worms who can tolerate higher temperatures than the European Nightcrawler.

Red wigglers have the highest reproduction rate at 25°C (77°F). This is helpful as higher temperatures also mean faster decay of plant based food, providing more food at this temperature.

The overall working range is 15°C-25°C (59°F -77°F) which means feeding and therefore producing worm castings and also cocoon production.
Tolerable temperature: 
absolute minimum: 0°C (32°F) (cocoons can still hatch after having been frozen when temperatures get warmer)
Maximum: over 27°C/ 80°F depending on length of exposure and humidity   

More about Temperatures for red wigglers here.              
The preferred habitat of the Euro is not just the surface but he also likes to dig deeper. His ideal temperature is 15 C.

It is also likely to produce overall more hatchlings than the red wiggler at lower temperatures.
More research here.

Life Cycle
Under ideal conditions (based on lab studies, 25°C):
Number of cocoons per worm: 130 cocoons per year, so roughly every 3 days a new cocoon per worm
Hatchlings per cocoon: average 2-3 
(up to 9, I regularly see 3-6 hatchlings per cocoon)
Time from cocoon to maturity: 44 to 90 days

If you start with a population of just a few hundreds mature worms, the red wiggler can double its population of adult worms within 2 months in addition to having hundreds more young worms by then.

Read more on How to breed red wigglers fast here.
The life cycle of the euro seems to show more variations in how long it takes to hatch and grow to maturity. Under ideal conditions (lab study, same conditions as for red wiggler, at 25°C)):
Number of cocoons per worm: average 0.28/ day, so roughly 100 cocoons per year, of which less than 20% hatched when incubated at 25°C) 
Hatchlings per cocoon: 1, rarely 2
Time from hatching to maturity: 30 to 130 days!
In a nutshell: fewer cocoons and hatchlings and longer time to maturity than red wiggler at 25°C.

Can you mix euros and red wigglers?

Yes, you can. The euro should add more aeration which is especially helpful in deeper bins including stacked systems where the weight of the upper trays can lead to compacted compost in lower trays. 

In terms of reproduction, there is no worry about mixing them either as they will not produce any hybrids. However, this study suggests not to mix different species because they will waste energy mating with each other. This should only be an issue if you want to grow the worm teams but not the composting.

Conclusion

It’s not easy to distinguish the red wiggler from the European Nightcrawler without some experience of one or the other. At first glance, they look very similar in colour and shape. However, if you have mature worms the nightcrawler will stand out in size. He’s almost double in weight, the body feels more like a little muscly snake in your hand whereas the red wiggler is more dainty and feels more like a piece of rolled up wet mini dishcloth (still working on that analogy – feel free to give me your own).

If you are mainly interested in composting then both can be held together without problems.

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