how to make roost less smooth

[rosemarythyme]

This seems to suggest that wrapping the roost can deter mites:

Hence why I said it was a possibility. The article writer seems about as certain as I: "wrappings may also deter red mites". My guess is if it's wrapped snugly it could minimize any gaps/crevices, which are what the bugs want to live in, but if wrapped loosely it could increase the amount of gaps (by providing a space between the wrap and roost, and wrap-to-wrap).

 

[theoldchick]

I've wrapped those kind of roosts in duct tape or hay strings to help keep them 'grippy'.

 

[Iluveggers]

What about sports grip tape used for baseball bats & hockey sticks?

like this here: https://www.dickssportinggoods.com/p/easton-bat-tape-16etsustnbttpxxxxbta/16etsustnbttpxxxxbta

 

[Hermits Garden]

There's a paint / sealer for truck beds that is offered in both smooth and textured. There are also textured "non-slip" paints for decks and stairs. I'd try those, so--no crevices, plus a good sealer on the dowel wood. If they "smooth it out" after another year, you just scrape and add another coat.