One insect widely used in scientific and medical research is the fruit fly, or Drosophila melanogaster, a 3mm-long insect of the kind that accumulates around spoiled fruit. It has been used in genetics and developmental biology for almost a century, and today several thousand scientists are working on many different aspects of the fruit fly. Its importance for human health was recognised by the award of the Nobel prize for medicine in 1995, for work on the genetic control of early embryonic development. Mutant flies with defects in any of several thousand genes are available, and the entire genome has recently been sequenced. These creatures have also helped to develop drugs designed to combat pathogens responsible for a range of diseases from skin infections to pneumonia and meningitis. Recent research with fruit flies has focused on the pathology of Alzheimer's disease; although the flies have a very simple brain they have highly developed muscles and nerves.
See AnimalResearch.info on Drosophila