For the last two years we have been using a couple of polystyrene beehives from Paynes. They are great value and appear to provide better winter protection for the bees. However we discovered one strange feature this year when we came to do our first spring inspection; slugs and worms had made their way to the top of the brood box.
We found them along the edges where the frames rest and some damp was held. It was unclear if the damp was from rain which had made its way in between the boxes or if it was condensation. We will need to talk to Paynes about this as we only found this feature in the poly' hives and all the wooden ones had just the normal odd woodlouse.
The bees did not appear to be making any efforts to get rid of them but, obviously, we flicked them all out and hope they will not return!