WATER VAPOUR PERMEABILITY OF NEST MATERIALS FOR THE PROPAGATION OF MEGACHILE ROTUNDATA
G. H. RANK
A high water vapour permeability is desirable for nest material, to discourage the growth of fun&!. The water vapour permeability was evaluated of pine, moulded expanded polystyrene (EPS) ana machine EPS, by calculating the loss of water from saturated wooden dowelling sealed in nesting tunnels in a block of the materials. Water loss was greater from dowelling at the side or end of blocks than at its centre, where it was 31·3% in pine and 7·1% in moulded EPS, per 24 h. For machined EPS of densities 16 kg/m3 and 24 kg/m3, it was 20·0% and 13·7%, respectively.