First on the Scene

A shiny green fly sponging up nectar from a fennel flower head

A shiny green fly sponging up nectar from a fennel flower head

The other day I was out in the garden taking pictures when a shiny green fly caught my attention.  Green bottle flies (Diptera, family Calliphoridae, genus Lucilia) are a bit larger than the ordinary house fly.  The adults feed on nectar and are pollinators, but because of their life histories, they fill some really interesting roles in the realms of human sciences.

One piece of news I found particularly interesting is related to newer use of Lucilia illustris in Maggot Debridement Therapy.  This $50 term refers to putting young maggots on a wound because will consume only dead tissue — fear not, they are reared under clean laboratory conditions.

[Pausing for readers to get past the “Eeuw, gross!” moment before moving onto the really interesting stuff.]

The news is that these larvae are exceptionally good at helping patients recover from bad MRSA infections.  A University Manchester study found that thirteen diabetic patients with nasty foot sores were able to heal up in an average of just 3 weeks, instead of the usual 28 weeks!  Not only do they clean up the dead cells that would just fester and decay, but they also get rid of the bacteria directly, and help stimulate the healing process.  As the article points out, this means that patients don’t have to deal with some of the side effects of strong antibiotics.  My daughter has dealt with several staph infections, including an episode of MRSA, so this ranks a big w00t!

Yes, these are the same sort of fly larvae, AKA blow flies, that help clean up dead animals in the environment.  Not only do the larvae need the nutrients from dead animal tissue to grow and mature, but the females need the extra maternal protein for egg production.  (Unfortunately, they are also pests in the world of sheep ranching.)

Which leads us to another famous use of flies, forensic entomology.  Calliphorid flies are attracted to blood or other fluids, and are the first to colonize a corpse. The rates of maturation for various species of flies have been extensively studied.  By examining the age of the larvae, comparing this with the conditions where the body was found, and the known temperature data to calculate the Accumulated Degree Days, the Post Mortem Interval or PMI can be determined.  The PMI is  how long it has been since the person died.

Blow flies may be “icky”, but the smallest of details can make great differences in the affairs of humans.

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