Some insects and arthropods frequently pose a serious risk to human health. They can cause painful bites and transmit some pathogens causing serious diseases such as malaria, dengue hemorrhagic fever, lymphatic filariasis, Lyme disease, river blindness, etc. Since the protective vaccines have not yet been available for most of these vector-borne diseases, vector controls are therefore the main strategies to prevent the diseases. Such plant-based products have been used in the control of insects of public health importance for centuries. However, the development and use of phytochemicals attracted considerable attention from researchers and industrial concerns in the last quarter of the century. Examples of major plant-based products used in pest control are pyrethrins, neem constituents, as well as many plant volatile essential oils for repelling hematophagous insects affording personal protection of humans from biting arthropods and noxious insects. The public has the perception that plant-based and other natural products are environmentally friendly and safer to use for vector control or apply to human skin as personal protectants than synthetic chemicals. Considerable advances have then been made in formulating phytochemicals to increase their efficacy, providing protection and acceptability in public health. In this chapter, we will dwell upon the research and development efforts leading to the development and use of plant essential oils for personal protection from anthropophilic insects and arthropods as well as the development and application of phytochemicals for the control of adult and preimaginal stages of disease vectors.