Economically important insects include pests of plants, animals and stored products as well as insects produced commercially (honey bees, silkworms, insects for fish bait and food for birds and zoo animals). Other insects are produced in large numbers for experimental purposes, biological control of insect pests and weeds and the production of sterile insects for population suppression. Insect viruses may affect morphology, physiology and behavior, often reducing longevity and reproductive potential. Thus insect viruses can be used as biological control agents of pest insects. Insect viruses may also interfere with the production or function of biological control agents (e.g., parasitoids and predators) and insects used for research purposes. Therefore, it is advantageous to screen commercial and research colonies and imported insects for viruses.Electron microscopy of negatively stained specimens (NS EM) offers a relatively rapid and inexpensive means of screening populations of insects for the presence of viruses or viruslike particles and to monitor the progress of virus control programs.