Trichomycetes are fungi that live obligately within the guts of many kinds of arthropods such as crustaceans, millipedes, and insects. The nature of the relationship with their hosts is not known in most cases although there is evidence that some of these fungi can kill their hosts whereas others may benefit them by synthesizing sterol nutrients required by the host. Dr. Robert Lichtwardt of the University of Kansas is one of the few specialists in the world working on the taxonomy and biology of these commensalistic fungi, and it is his efforts over the years that have led to the present stage of knowledge about them. In continuing studies of Trichomycetes, Dr. Lichtwardt is surveying their occurrence in aquatic hosts in two widely separated regions, Australia and New Zealand and in Costa Rica. Preliminary work by him has indicated that new species of fungi, and possibly new genera, occur in both regions, and with varying levels of specificity toward their hosts. Efforts to culture the fungi under controlled laboratory conditions will continue, along with studies to determine their complete life history, including processes by which fungal spores are dispersed and come to infect appropriate host arthropods. Dr. Lichtwardt's studies also contribute to the inventory of microbial organisms in the world, especially of tropical regions, an inventory at present very incomplete.