Below is what I found upon googling. NOT SURE IF info is correct or not. I used to think an earthworm is an earthworm.
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"Perionyx excavatus are undesirable to home composters and bait worm sellers. They will compost in warm outside conditions but take over worm beds and drive the E. foetida out. They never ever get big enough for bait. They migrate for no reason even during daylight or with bright lights over them. They will be all over the floor in school or home bins. They are very undesirable for tropical fish food. Cold temps kill them." Dan Warco of KAZARIE Worm Farm Happy D Ranch does not nor will we ever sell P. excavatus worms. We consider them an invasive species that has done a great deal of harm to the vermicomposting and bait industry. Many unscrupulous businesses sell the P. excavatus to use in worm bins. The well intentioned but uninformed purchaser wakes up to find worms everywhere but inside the bin. They think they did something terribly wrong but it was the dishonest grower that knowingly sold them the wrong worm for the worm bin that did something terribly wrong.

More than 4,000 species of earthworms have been identified, yet only six species are suitable for vermicomposting. Of the six species, only one is used most commonly in North America: Eisenia fetida (red wiggler). It is very important that this one species of earthworm (or its "cousin," Eisenia andrei) is used for vermicomposting, so do not pick up earthworms in the environment and put them in your worm bin. Instead, purchase red wigglers from a worm grower (click below on Directory of Vermiculture Resources).

P. excavatus are great composting worms if you know what you've got. (they're obviously a huge PITA if you think you got EF) They breed faster than any other composting worm species and swarm food if the temps are good. However, they do tend towards mass escapes, especially in new worm bins. But they're not the only species to do so. E. eugeniae (African nightcrawlers) and E. hortensis (Euros) will also escape new bins.

The simplest solution is to apply a salt jelly fence.

Andrew

The same thing happened to me. They are great composters, but I have to vacuum escapees off of the floor almost every day.

"I have to vacuum escapees off of the floor almost every day"

OH NO...why don't you put the earthworms escapees into your garden soil directly. THAT is what we all are trying to do here, right, with vermicomposting. The end goal is to increase earthworm population in the earth so that soil is soft, moist, aerated, organic, oxygenated and healthy for the plants.

Please DON'T vaccum and kill them. Put them into your garden soil. During winter they will either die or go deeper into earth where it is warm.

You do realize that these composting worms are not earthworms, right? They require manure (in nature) or garbage (in vermicomposting systems) to survive.

I've got some in my garden soil because I am sloppy about harvesting the castings, but there has to be a lot of organic material for them to survive. They aren't going to be doing much to aerate the soil if I understand the basics of wormology. I think most people, if they go to the trouble of collecting escapees, will be returning them to the bin and not the garden.

I'd be interested to know, in nature, where / how do these worms survive when the supply of manure runs out? There aren't any dung heaps in nature, they must show up when an animal dumps its load... Are they already present as cocoons or living nearby?

Not to get too technical about definitions, but I think "earthworm" is very broad and does cover the common composting worm species. Here's a short article on some of the major differences:
http://thegardenforums.org/viewtopic.php?t=126

Since the vermicomposting species do not create permanent burrows, they will not help in aerating garden soil. I imagine that these species lay tons of cocoons when either food is running out or the environment turns bad for them (high or low temps, no moisture, etc.). The cocoons can tolerate much harsher conditions and simply wait it out until food supply and conditions become favorable again.

Andrew

Please don't get on my case for vacuuming up the escapees. When they escape during the night, by the time I find them in the morning, they are dead and dried out.

sbryce, didn't mean to "get on your case". Just that we spent lot of money on getting the worms...I thought it could be "recycled" lol.

Colesvilled:

Agreed with ya.

The composting worms are also type of earthworms, are distinct from soil-dwelling earthworms.

"Now, if you wanted to improve a plot of soil by increasing the earthworm population therein, and someone sold you redworms for that purpose, I believe that both Werner and Bhawalkar would shake their heads, NO! No matter what you call it, it's not the right worm for that function. Simple and clear."

Matthew Werner, staff researcher in the Agroecology Program at the University of California, Santa Cruz has stated (Worm Digest #5, "Real Earthworms") that the redworm should be called an earthworm as it lives in the soil, albeit the "surface layer of fallen plant litter," which he considers a part of the soil. Due to this location of habitat for the redworm he refers to it as an epigeic species, but an earthworm nonetheless

Earthworms are classified into three main ecophysiological categories: (1) leaf litter/compost dwelling worms (epigeic) e.g. Eisenia fetida; (2) topsoil or subsoil dwelling worms (endogeics); and (3) worms that construct permanent deep burrows through which they visit the surface to obtain plant material for food, such as leaves (anecic), e.g. Lumbricus terrestris.[11]

Just an observation: As Ef vermicompost has been added to raised beds and heavily mulched to inhibit weeds, the hatching wigglers seem to do OK. They may die off somewhat with colder weather, but are back each spring. So they may benefit the soil indirectly by aerating the materials under the mulch covering (but not so much in the soil itself) and the addition of the beneficial micro-organisms can't possibly hurt the soil as it leaches down. I suppose if the beds were covered with straw in the winter the worms would eat that also.

Yep...the whole discussion then whether

1) Perionyx excavatus(PE) are good in vermicompost bin...should we panic? Is it "invasive" as some claim on the net?

2) whether Perionyx excavatus(PE) do well in soil.