What was it?

August 14, 2014 • 12:44 pm

What was this monstrous thing I put up this morning?

It’s the larva of a bluebottle fly (Calliphora vomitoria), of course. You didn’t know that???

Normally, adults lay eggs in carcasses, and the larvae develop on the rotting flesh. They aren’t like blowflies that burrow in and grow on living flesh. But as the note below says, their penchant for dead flesh makes them medically useful. What a clever way to take advantage of an evolved feature!

Screen Shot 2014-08-14 at 6.54.23 AM

This photo appeared in the Torygraph (h/t to reader pyers), with this note:

A coloured scanning electron micrograph (SEM) of the head of a maggot or the larva of a bluebottle fly (Protophormia sp.) with tiny teeth-like fangs extending from its mouth. The maggots of this fly are used medicinally to clean wounds. The maggots are sterilised and placed in the wound, where they feed on dead tissue and leave healthy tissue untouched. Their saliva contains anti- bacterial chemicals which maintain sterility in the area. Maggots are used on ulcers and deep wounds away from organs or body cavities, most often being used to treat diabetic ulcers on the feet

Picture: EYE OF SCIENCE / SPL / BARCROFT MEDIA

Be sure to look at the other photos in that Torygraph gallery of insects and spiders.

42 thoughts on “What was it?

  1. What is its correct Latin name? The Torygraph has Protophormia terraenovae but Prof CC has Calliphora vomitoria.

    1. Those are actually two different species of fly, but the name, “bluebottle fly,” is commonly used for both. I don’t know who is correct regarding the identity of the critter in this micrograph though, Jerry or the Torygraph.

      Calliphora vomitoria is a much cooler binomial though.

  2. A infantryman who fought in the trenches in the ’14-’18 war records how these larvae saved the lives of wounded soldiers trapped in foxholes. The larvae removed rotting flesh from their wounds thus preventing the spread of gangrene.

  3. “The maggots are sterilised and placed…” I thought they used specially bred clean ones- how on earth does one sterilize a maggot?

    1. I would guess dipping them into a dilute solution of bleach. The larvae are very tough, and I doubt they would mind it very much.

    2. Radiation. X-ray exposure was used during the first tests at Sanibel Island, Florida. I could assume it is still the method in use, since the human hazard stops when the tube is switched off, unlike nuclear sources.

      1. Oops, that’s for the screwworm program. Cochliomyia hominivorax were eradicated by sterilising and releasing infertile male flies.

  4. But how do these maggots know what is dead flesh and what is alive? I’d presume that it can’t just be “dead” but would have to be putrefying flesh that presumably has some identifiable chemical signal, as otherwise they should start eating the dead surface layers of skin, for example.

    1. These maggots don’t have little jaws to nibble. They exude compounds that dissolve the necrotic tissue so that they can slurp it up. Technically speaking.

      I’ve seen pictures where they’ve been used medically with great success in cleaning out the tissue from diabetic ulcers on people’s feet, which are apparently very difficult to treat.

  5. It still looks unreal to me, but I do like it!

    Good to see those of us who speak proper English instead of American are having an influence on Jerry – “coloured”!!!

  6. A coloured scanning electron micrograph (SEM)

    One wonders how exactly the colouring was arrived at. Such things are rather difficult to do “accurately” (for any defined degree of “accuracy”).

  7. Well, this certainly provides another example of not judging a book by its cover. “Disgusting maggot that grows fat on rotting flesh” turns out to be a clever and efficient boon in medicine. Truly, our stereotypes are mean little things.

  8. http://www.fao.org/docrep/U4220T/u4220T0a.htm

    This is an account of the eradication of Cochliomyia hominivorax. Sometimes called the primary screwworm fly. It infests wounds and feeds on living flesh. I’ve seen reference to the necrotic flesh feeders as secondary screwworm flies.

    I grew up on a ranch in screwworm country in Texas. I well remember having wormies in the pen and doping the wounds with “black daub” to kill the maggots. The eradication program started after I went off the the university. Daddy told me the sterile flys were dropped in small cardboard boxes. You could tell when there had been a drop because they were “friendly flies” and would cover the kitchen screen door. The program was paid for, in whole, or in part, by checkoffs of sales of livestock products by ranchers.

    The successful eradication program traces it roots back to Mueller’s experiments with using radiation to stearilize fruit flies.

    One result was an explosion of the whitetail deer population in Texas. Leasing land for deer hunting is a big economic thing these day. My ex pasture land is on its fifth owner, who bought it as a hunting preserve. He leased grazing rights to a neighbor.

    1. When I was employed at UT, the prof I was working for–Guy Bush–along with a cohort, Barrie Kitto, were involved in solving an interesting problem that arose with that program. This is how I remember it, though it’s been a long time and I may have some facts wrong.

      The sterile fly project involved the release of masses of sterilized males, which by virtue of numbers would be more likely to mate with female screwworm flies than the natural males would. Such matings, of course, produced nothing viable. While the program was initially quite successful, after a while the effect started to wear off, and Guy & Barrie were consulted about determining why .

      Guy is a population biologist who looked at speciation and other aspects in part by collecting sample organisms and examining alleles (or more properly, “electromorphs”), via gel electrophoresis. Barrie was in the chemistry department and versed in enzyme kinetics.

      At this time the flies were being raised in Mexican labs, apparently in chambers filled with hanging strips of–plastic?–on which the flies could spread out so that a lot could be raised in a smallish area. At some point the temperature of the chambers was raised to speed up the generation time.

      When Guy ran gels on the flies, it turned out that the lab flies had a larger proportion of one alpha-GPD (alpha-glycerophosphate dehydrogenase) allele, while the wild flies had a preponderance of a different one. (alpha-GPD, for one thing, is important in muscle metabolism.)

      Barrie than looked at the temperature optima for each locus and found that the hotter labs had selected for an allele whose optimal “operating temperature” was higher than that of the wild flies. So when lab flies were dropped in the cool of the morning, they would sit around on the ground till their large thoracic flight muscles got warm enough, while the wild flies were meanwhile flying around, fertilizing the females again.

      So the fix was simply lowering the lab temp. One of those tidy stories that are so satisfactory.

      (Now Jerry or Matthew or someone will let me know just how wrong I’ve gotten things.)

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