The common green bottle fly

If a green bottle fly was asked, "Who goes there?  Friend or Foe?", its answer would be, "Both."  This insect is on humanity's radar for multiple reasons, although most of us would consider them pests rather than beneficial insects.

The pest perspective is well warranted.  Carriers of disease and harbingers of decay, these flies are found where rot exists.  The maggots feed on dead tissue, both plant and animal, but are most commonly associated with discarded organics.  The flies are often the first organisms to invade the corpse of an animal.  Adults feed off the superficial liquids extruding from such bodies while the young bury themselves in the mass facilitating decay and gorging off the remains.  Bacteria, moulds, and other carriers of disease hitch a ride on the adults as they travel between meals.  Then it lands on your dinner plate, skin, and even your meal. Yuck.

What about the benefits these winged vectors bring?  Notice the photograph above; the adults facilitate pollination.  Flying from flower to flower to collect nectar as a food source, they transmit pollen in a manner similar to bees.  These flies are also important in nutrient cycles.  They help with the process of decay and turn dead matter into new life.  Nutrients are returned to the Earth and dissipated over distances as emerging adults move to other areas.  Consider the many organisms that eat flies.  Birds, amphibians, reptiles, other insects, and even fish feed on them; they are an important component of the food web.

Then there are the uses man has put to them.  Green bottle fly maggots consume dead flesh and generally don't bother with healthy tissue.  They have been used by modern medicine to consume decaying tissue around living tissue as a means to clean wounds.  Even police have found a use for them.  The green bottle fly's life cycle can be measured in days.  Egg goes to newly hatched larva to instar maggot levels between 1 and 5, pupate, and then emerge as an adult.  Each stage takes a certain amount of time and crime scenes can be dated based on their development.  Just watch Dr. Hodgens on an episode of Bones.

I think it can be safely said that green bottle flies are beneficial organisms that can cause problems in certain circumstances.  They are less likely to be a problem if rotting substances are kept in isolated containers and removed frequently.  They are important components of nutrient cycling in the ecosystem and in most foodwebs on the planet.  It's also kind of pretty, don't you think?

Thanks for reading.

Eric Svendsen     www.ericspix.com