Floating top

I use the "floating lid" principle for insulating the top of the worm bin. By cutting the lid to fit inside the bin and rest on the surface of the bedding, it retains some of the heat that may be generated, rather than letting the heat dissipate to the space between the top of the bedding and the bottom of the closed lid. Space around the edges lets air in so the worms don't suffocate and the bacteria, fungi, protozoa, nematodes, springtails, enchytraeids and sow bugs can get their required oxygen.