Thousands of arthropod species use plants as their main food source. Plants in turn are not completely passive towards arthropod herbivory. Arthropod saliva constitutes an important point of contact which initiates phytophagy and mediates chemical communication. Here we present a summary of those communications studying the constituents of arthropod saliva and their effect on plants. Particular attention has been dedicated to those reports identifying salivary gland genes and proteins in their entirety (transcriptomes and proteomes). The anatomy of salivary glands is highly variable and much of its complexity remains unstudied in various groups of phytophagous arthropods. Some important factors dictating the function of saliva in herbivory are the feeding strategy used by the arthropod, the developmental stage of the animal and the ecological niche in question. The function of many salivary components, such as the chemosensory proteins identified in arthropods, is still largely unknown. We consider the use of heterologous expression of these genes, chemoinformatic, molecular modeling and immunohistochemical studies to be of substantial importance for the elucidation of the functions of these genes as well as the functions of many other unknown proteins in arthropod systems. Additionally, the role of hemolymph proteins such as apolipophorins and storage proteins in saliva is unclear and therefore attention must be devoted to the understanding of protein movement in the arthropod body.