Our laboratory studies the neuronal and behavioural reactions of the Eristalis tenax hoverfly when presented with specific visual stimuli presented to it. In nature, Adult E. tenax hoverflies pollinate flowering plants whilst larvae consume decaying organic matter, such as faeces.
Although some fly species can be harmful to both humans and livestock/wildlife, others are beneficial to human society. The fruit fly Drosophila melanogaster is regularly used in scientific research, due to the vast knowledge in its genetics and behaviour, in addition to its short life cycle, which allows observation of inheritance patterns over relatively short periods of time1. In the wild, other flies are excellent aerial predators, capable of identifying and seizing prey mid-air, such as Robber flies2.
Flies are currently used in medicine and forensics. Maggot, or Larval therapy, is a traditional medicine technique used to treat chronic/long term wounds. Maggots (or larvae) of specific fly species are placed on the wound to feed exclusively on the dead flesh, to allow the wound to heal on its own3. The green bottle fly (Lucilia sericata) is the species most commonly used for larval therapy. The larvae are disinfected before use (via disinfectants) for patient treatment4.
They are then placed onto the wound directly with gauze/bandages, or in small packages (similar to tea bags) so that they are contained but are permeable to the enzymes they secrete. After 2-3 days the larvae are removed, and replaced with new larvae if the wound still has infected tissue4. Larval therapy is particularly important because it reduces the need for surgery to remove dead tissue – one attendant can apply and remove the maggots to the wound (with gauze/bandaging to trap the larvae)5.
Forensic entomology is the study of decomposition of corpses by the insects that feed and breed on them, and can reveal a lot of information about a corpse6. Blood removed from the gut of blood consuming insects can be sequenced to identify victim’s movements (e.g. a blood splatter that the bug consumed)6. Insect larvae can be used to identify toxins from corpses that scavengers have fed from and tissue fluid is no longer available to sample, as the compounds are absorbed by the larvae6.
Blow flies and flesh flies are among the first insects to find a corpse, sometimes within minutes of death, detected by their keen sense of smell7. Both flies complete their life cycle in carrion/corpses; pregnant females lay eggs (blow flies) or larvae (flesh flies) onto the corpse7. Larvae then feed on the corpse, after which they complete they pupate in soil, before finally emerging as adults7. Other insects are found on the corpse after blowflies/fleshflies, such as beetles, and vertebrate scavengers such as vultures7.
- A National Geographic video showing the application of medicinal maggot therapy on an infected wound in a diabetic woman. WARNING: Graphic video. https://www.youtube.com/watch?v=3mDXfQ6zKD0
- https://www.youtube.com/watch?v=HIVKISCmjTQ a short video that describes the insects studied in forensic entomology and their life cycles.
- https://australianmuseum.net.au/learn/science/decomposition-fly-life-cycles/ for more forinformation on how insects are used in forensic entomology.
An article describing why fruit flies are essential to scientific research.