We pick our own night crawlers in Vt starting in April and May. On a good rainy night you can get hundreds or even thousands of them depending on the temp and the place. I like old established lawns like in cemetaries, golf courses or public greens. I built a 4' x 2' box about 1 1/2' high and stapled a screen on the bottom so it drains. Fill it with a small amount of top soil, wet grass, leaves, moss and most anything else that is organic. I do better if the mix is light and can easily be turned by hand. I keep it covered with an old tarp about a foot over the box to provide shade but still allow for ventilation. Keep it wet and sprinkle some coffee grounds in every few weeks and rotate or mix it all up by hand. Never put any damaged ones back in the worm bed. When I use some I usually take what I need for the day and put them in a small insulated bait box. I use them all or put the remaining ones in the garden. If you get lots of dead ones they will spoil your worm farm so keep them all fresh. When the worms start to run out wait for a rainy night and get some more to refill the box.