Sorry about the large cut and paste.
https://www.redwormcomposting.com/reader ... -backyard/
There are three basic groupings of earthworms â€“ 1) â€˜Anecicâ€˜, 2) â€˜Endogeicâ€˜, and 3) â€˜Epigeicâ€˜. The anecic worms, such as the large â€˜Canadian Nightcrawlersâ€™ (aka â€˜Dew Wormsâ€™ â€“ Lumbricus terrestris) build deep burrows, typically extending down to the mineral soil layers. They live a relatively solitary life (coming up the the surface for feeding, mating, and to escape from flooded burrows), and generally thrive at cooler temperatures than those worms in the other two groups.
Endogeic worms are basically the intermediates between the other two groups. They are still soil worms, but are typically located closer to the soil surface. Unlike the anecic worms, they often create horizontal (rather than vertical) burrows.
The last group, the epigeic earthworms, are of course the ones we are most interested in from a composting stand-point. This group generally lives at or above the soil surface â€“ typically associated with concentrations of rich organic matter (eg. leaf litter, manure etc). They also tend to be much more tolerant of crowded conditions and wider fluctuations in temperature. Because they live in these potentially harsh/challenging environments, epigeic worms also tend to grow and reproduce much more quickly than the other groups of worms (helping to ensure the success of future generations).
You are certainly on the right track with your approach, Francisco. If there ARE any epigeic species of worms located on or near your property, there is a decent chance you will be able to attract them to an area where you have added organic matter on the soil surface. Whether or not you will attract the best species and/or enough worms to make your efforts worthwhile, is another matter altogether.
I know that if I did the same thing in my own yard, I would end up with lots of Red Worms (Eisenia fetida) concentrated in the organic-material-rich-zones. As an illustration, I recently left a few (freshly harvested) zucchinis on my lawn for a day or two. When I went to collect them, I discovered a handful of small Red Worms underneath each of them! I can only imagine how quickly I could populate a heap of aged manure if I dumped it on my lawn!
If one of your neighbors happens to be composting with worms, or if they have found their way into the area via some other means, you may be in luck! More than likely though, you will end up with a mix of epigeic and endogeic species that just happen to be living close by.
The fact that youâ€™ve found some small reddish worms could be a good sign, but the only way you will know for sure if they will work is to put them to the test in a worm bin. As for them coming up under your cardboard â€“ this is pretty common for most types of earthworms. Leave just about anything to sit out on your lawn for long enough, and youâ€™ll likely end up with quite a few worms congregating underneath.