There aren't any listed this month, but occasionally someone lists them on the fish & egg listing of the American Killifish Association (http://www.aka.org/pages/FEL/currAKAFEL.pdf). Additionally, they advertise starter cultures here for $7: http://www.creatureville.com/insects/white worm culture.htm. However, I've never dealt with them.
White worms are a bit harder to culture than grindal worms because their ideal temps are in the high 50's to low 60's. Additionally, cultures can crash seemingly overnight, and springtails invariably invade a culture and sometimes outcompete the worms for food. Best of luck, though, as they are definitely a good source of protein.
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Homer W. Faucett III, esq.
Purveyor of Trivialities and Fine Nonsense