Pests cause economic damage to crops and stored products, while vectors are responsible for the transmission of disease-causing agents in human beings and livestock. Although the application of synthetic pesticides in agriculture has given immediate relief, it has also caused well-known side effects, leading to a general consensus among entomologists and agriculturists to shift towards other ecofriendly pest management. Insect natural enemies consisting of predators, parasitoids, and pathogens have attracted the attention of scientists across the globe. These natural enemies exist in agroecosystems and suppress the populations of pests. Parasitoids are farmers friends and the most successful group of natural enemies. Highly specialised in their host choice, the female parasitoid searches for a suitable host to lay eggs and larvae in, on or near the hosts. Exploiting this potency of parasitoids may yield successful results in controlling notorious pests in an ecofriendly way.This book covers information on the important biocontrol agents effective in pest suppression. It starts with insect parasitic groups followed by specific groups of parasitoids. It is hoped that the book presents a comprehensive account of beneficial parasitoirds, and will be useful to undergraduate and postgraduate students of Entomology, Biological Control, Plant Protection, Agricultural Zoology, and Zoology, besides those involved in competitive examinations and policy planning.