I here ya...its really dry here in ND during the winter...
Although I stopped breeding roaches years ago. I imagine spahgnum moss would do a fine job. Ground coconut would be good as well, and could be sifted, although after a given period of time would have to be replaced.
I always found blaberus.com to be a bounty of info.
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Jeremy Payne
JB Reptile
1.0 Snow "Kahl"
0.2 Triple Het Moonglow "Kahl"
0.1 Orange Tail Hypo Het Leopard
0.1 Double Het "Sharp" Snow
1.0 Ghost
0.1 Possible Super Hypo
0.1 DH Ghost
1.1 "Kahl" Albino
1.0 Hypomelenistic
1.3 Pastel Hypo
0.1 Anerthrystic
1.1 Morelia Clastolepis