Red Californian Earthworm, California Redworm or Red Wigglers
The Californian Redworm (Eisenia fetida) is a worm about 15 cm in length and usually more than two millimeters in diameter. It lives at low depth on the ground and adapts perfectly to captivity and overcrowding. Despite its name, its original area of distribution is European and Asian, but given the universality of its cultivation, it is currently cosmopolitan, without causing any danger to the natural populations of the same group, so it is not considered an invasive species.
The red worm is able to tolerate very high levels of humidity, above 90%, but does not resist humidity below 60%. It is also photophobic but does not go deep into the substrate. It feeds on any organic matter as long as it is sufficiently moist and well attacked by microorganisms, which actually represent the main food of worms. They eat an amount of food similar to their weight per day, which means that each individual transforms 0.3-0.5 grams of organic matter per day. Given that a bed of worms can have more than 10,000 worms per square meter, it is easy to understand the enormous amount of organic matter that can be transformed.
Red worms live 5-6 years (enough to be an invertebrate), although often the informative literature speaks of 15-16 years, which is totally false. Having an appropriate substrate, approximately every week the earthworm produces a cocoon that harbors 2-3 embryos (not 10-20 as also stated). Frequently, some commensal nematodes that feed on amniotic fluid can be seen in the cocoon. They are harmless to worms in formation and are easy to confuse with earthworms in ovo. As soon as the small worms hatch, they suck the food they find in their environment, growing rapidly. In three months, they are already fertile and, like their parents, produce a cocoon every week. This makes the demography exponential, and that even starting from a small amount of worms, after a year you can have a good production of them.
But it's not always that easy. In the trophic ecosystem there are numerous organisms that share similar habits, most are commensals, and some are true enemies of earthworms. The friendliest neighbors feed on organic matter and even contribute feces that facilitate the digestion of worms; among these species, there are moisture cochineals, fly larvae and some beetle field larvae. The same can be said of some white mites and especially springtails, very frequent in the substrate, remarkable for their continuous jumps. Also the edaphic nematodes feed on organic matter and collaborate for a good quality of humus. However other residents are fearsome. Among them: ants, green crickets, carnivorous flies, red mites, spiders and scolopendras. All of them must be eradicated. Other unpleasant and very dangerous neighbors are the voles, some birds (watch out for chickens, little egrets and blackbirds) and toads, which must be monitored and expelled from the ecosystem.