Information relevant to the U.K. and Ireland
Polystyrene (poly) hives are becoming so popular in the U.K. that I have asked John Laidler, who has great experience of poly hives, to write about them. Poly hives have been used in some other countries for some time, with popularity in colder areas such as Scandinavia, where they outsell wooden hives. I don't think they are popular everywhere and in Switzerland, where I would have thought they would have been of benefit, I was told they don't use them much because of woodpeckers and mice. This surprised me as they are both a problem with wooden hives as well.
Although I have never owned poly hives, I have handled bees in them on many occasions and have known beekeepers who use them. I have some concerns about them and I won't be changing from wood myself. It may be my concerns aren't valid, or they may be easily overcome. I certainly don't want to put anybody off using them.
There are claims that bees are warmer in the winter. If so, I assume there is more brood, with possibly no brood break. Although this may appear an advantage, I wonder if it means that oxalic acid isn't as effective as it would be if there was no brood.
It is my strongly held view that bees are very much softer than they were when I started beekeeping. I believe there may be several reasons for this, including the importation of the very soft yellow bees and the mollycoddling of them by beekeepers, allowing them to survive when natural selection would soon sort them out. I suspect that keeping them warmer may make the situation worse.
I have seen some poly hives that have been of rather poor quality and in my view too soft. As an engineer I don't think they would last very long and I have been very careful with the hive tool when inspecting them.
I have been the auctioneer at the West Sussex BKA auction since the 1990s where there has been an increase in the number of polyhives in the sale, which is consistent with their availability. In the 2015 sale there were several lots of polyhives that the seller has had for about 4 years. I know the seller well and I know they have been well looked after and were painted when he bought them new. I was very surprised at the condition of them, as the surfaces were crumbling and there was damage where the hive tool was used. They fetched about a quarter of new price.
Some are clearly not compatible with wooden or other makes of poly hive. This I think will be a problem, especially if a manufacturer ceases trading, or changes design.
Some poly National hives have handholds like the old style wooden Nationals. I think most people would find this a disadvantage as the weight of a full box is on the fingertips.
I have a positive attitude to most things and I have no problem with other beekeepers using these hives, after all I have been using poly mini-nucs for many years. It is up to the individual to use whatever suits them.