Termites are believed to be the oldest eusocial insects and their morpho-physiologically distinct castes are called reproductives, workers, soldiers and immature forms. Termites are called xylophages or wood-decaying insects but can also feed on a variety of organic materials, including grasses, litter, humus, and components of the soil, such as hydrolysable peptides and polyphenolic compounds. These specialised feeding habits of termites are linked to their digestive apparatus and allow them to act as primary consumers and decomposers (herbivores and detritivores). In this book, chapter one discusses the connections between digestive processes of termites and their feeding habits and ecological role. In chapter two, the functional morphology of the digestive tube of ten species belonging to seven genera of neotropical Termitinae is analysed, with the aim of characterising and comparing the configuration of individuals from different castes. The final chapter in this book discusses the physical phenomenon which causes the absence of mites at high altitudes in Europe. The aim of studies conducted in chapter three, is to systematically review the relationship between allergen exposure in Europe and altitude-related characteristics.