sglass is correct as I have seen that work. My grandpa dug a hole in the shade next to his garage, buried a styrofoam cooler and filled it with dirt from his garden. He would fill it with worms and put some wet shredded newspapers on top. Put the top on the cooler and put a decent sized rock on the lid to keep the animals out. This always worked. When he got older I would catch them for him and fill up this cooler which he could scoop out and have his worms ready.