ABSTRACT
F ew animals surpass the flies in intricate detail of construction, and few exceed their freedom of movement and diversity of activity. No animals, except perhaps people themselves, are responsible for greater loss of human life and economic loss than they are. More than 500Al of the world's population is diseased from flybome pathogens and parasites. Crop losses suffered each year because of pest flies are exceeded by those of few other insects. At the same time, extremely beneficial species exist, the parasitic and predatory habits of which aid in the population control of many pest insects; they rank in value with the parasitic wasps. The role of flies in the detritus cycle, processing dead plant and animal material, is exceeded only by that of bacteria and fungi.
