Hulls do not offer any nutritional value, so pests will not generally seek them out for food. Mites do not like buckwheat hulls as they provide too much air flow which makes an undesirable nesting site. Any mattress ticking can house bed bugs / dust mites but the open weave of our cotton ticking is also not a desirable nesting site for these tiny pests. You must maintain the underside of your hull mattress often so this makes it easier to catch any unwanted visitors.
The New Twist tubular fabric has tiny openings in the knit which would keep out larger insects. Just like a wool mattress company could not guarantee a moth may get to your mattress, we cannot absolutely guarantee an insect may find their way in somehow or a rodent may nibble at a pod to investigate the hulls for use in their own nests!
We have been working with hulls for many years now and we have heard of only one insect populating in a hull mattress (as well as the rest of the home); harmless booklice. Booklice are attracted to glue in books wallpaper and some glues in wood furniture and they thrive in moist environments. They are common in new construction homes and *a recent study found they are most likely already living in your home (98 out of 100 homes tested, booklice were found) so be sure to control humidity levels in your bedroom to keep their population in check.
Note we have had no incidence of booklice problem here at OYEB. We open every 10th bag of hulls for pillow filling so our hull inventory is monitored and we have never found anything undesirable in them.