"naturally occurring earthworms" what most of us here use to make vermicompost is compost worms. Earth worms burrow into the earth. Compost worms digest kitchen waste usually above or close to the surface of the earth. Cutting a watermellon, pumpkin etc. in half and placing it on the earth for several days, especially during the rain, should turn up maybe 7 worms each day, by looking under the mellon and gathering the compost worms.

For big worms, there are varities pf worms that are bigger than compost worms. A compost worm is only so big even when fed on corn meal for a week.

An outside bin, and even an inside bin are at risk for mice, etc.

If you gather worms for fishing, you can put them in a see through deli container with wet bits and pieces of egg carton on top of them. Maybe gather them a few days before your guests arive. When picking up the containers, all the worms will of migrated to the bottom and are easily viewable there. Way impressive even with just 200 skinny compost worms. Be sure to add air holes and store cool and in the shade.

Any worm is a good fishing worm, even skinny little red wigglers. You either use small hooks or use 3-4 at a time. I have caught large catfish with tiny worms and hook.

When I used to search for fishing worms, I would look in any manure pile. As long as the manire is damp, worms show up in a couple of months or less around here. Another great place to look is under ANYTHING laying flat on the ground for a few months or more. Old scrap of plywood, cardboard, old carpet, really anything. Use all that cardboard from your move. Dampen and layer thick, maybe something else on top to hold it down, and I bet they come.

If I were to start a worm bed from scratch here with just manure or compost, it would take about 3-4 months to get well populated with worms. Your climate and area may be different.

My worm beds have been "infiltrated" by rats, mice, ravens, chickens, moles, and something a little bigger that digs in some nights. I cover my wormbeds with old carpet and blankets and put heavier items on to weigh them down. I loose some, but I have plenty! Colteral damage is the military term.

Good luck and let us know how it goes. Pete