I found this on the web.
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Harvesting the worm is best from April through November, with the largest hatches produced in late spring and again in late summer. A single tree may hold 200 worms. To gather the worms, place a tarp or piece of plastic under the tree and shake it until the worms fall off.
The worm can be preserved alive by placing it in cornmeal or sawdust and packing it in a glass jar and frozen indefinitely. When thawed, they become as lively as the day they were froze. This is because their metabolism slows down while eating and, therefore, freezes in its natural state. Some fishermen report that it is better to freeze them in water in lots of 25. Thawed out, they turn black and soggy, but do not seem to lose their appeal to catfish.
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Dont know, going to try it.
-ttldnial