A laboratory study, dealing mainly with Reticulitermes lucifugus var. santonensis. In tests with filter-paper discs, most of the wood-rotting mould fungi examined had no inhibitory effect on the termites, but several wood-discolouring and insect-pathogenic mould species produced rapid death. Some species of white-rot fungi increased termite feeding activity. Several fat-soluble components and a water-soluble protein, all with toxic effects on termites,were isolated from mycelium and culture filtrates of Penicillium divergens. -- AATA