Cypress repels insects, definitely don't use it. It's too coarse, anyway.
Without knowing exactly what roaches you're getting, I'd recommend coco fiber. It's made from shredded coconut shells, and it's very soft, fine-grained, and good for a wide variety of burrowing insects. If you don't have it when your roaches come in, just give them some crumpled, lightly damp paper towels to hide under, that'll hold them over.