We reviewed the distribution, functions, phylogeny, diversity, and spatial and temporal variation of Wolbachia. Wolbachia are cytoplasmically inherited bacteria and widely found in reproductive tissues of arthropods. Systematic surveys of Wolbachia distribution and diversity are now possible using PCR\|based methodologies. The 16S rDNA and ftsZ studies have provided a number of useful molecular tools for such surveys. A survey of Panamanian rainforest insects and the members of two temperate hos...