I use both the wooden and the plastic insert miller feeders. The plastic insert provides beetles and sometimes bees to hide unless caulked or otherwise sealed between the insert and wooden box. They don't build comb in the plastic insert because the screen keeps them out. My wooden ones let the bees have full access which allows them to drain it much faster, but also allows them to build comb in it. The plastic ones will not give much insulation. I use the wooden ones when I want to feed extra heavy syrup during the winter. If you want the wooden ones to last longer, you can seal them with clear food safe epoxy available the major bee supply sites.