Knowledge of the bioreceptivity of wall paintings to microbially induced decay processes has increased considerably in the last few years. Indoor wall paintings are widely recognised as a favourable environment for microbial biofilms in general and for microscopic fungi in particular. This environment also provides a suitable substrate for insects, spiders and other arthropodas. A combination of mycological and entomological studies of indoor wall paintings demonstrates an important ecological correlation between fungi and arthropods in the developmental processes of this complex microbial community. The co-existence of microscopic fungi and arthropods on the surface of wall paintings suggests an ecological interaction between them. Faunal impacts on the growth of biofilms due to grazing and propagule dispersal cannot be overlooked. Along with the above-mentioned perturbations, arthropods can directly damage the wall paintings by bioabrasion during grazing on the biofilm, as well as by the production of dwelling cavities. In this publication, we present the ecological connections between the major microscopic inhabitants of these important objects of cultural heritage. The additional role of arthropods as a remarkable source of organic substrate (e.g., chitin, spidersilk and faecal pellets) available for many micromycetes is discussed.