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The Well-Groomed Fly (1977)

The Well-Groomed Fly (1977)

©1977, 2013 by E.H. Burtt, D. Denny, E.J. Molina, & Howell, W.M

Source: Burtt, E.H., Denny, D., Molina, E.J., & Howell, W.M. (1977). The well‑groomed fly (Musca domestica). Paper presented at Animal Behavior Society National Meeting, University Park, PA, 5‑10 June.




When I was in a graduate program in psychology at the University of Tennessee, Gordon Burghardt, my major professor, went on sabbatical. Jed Burtt filled his position for a year. As his lab assistant, I was required to procure a half-dozen or so houseflies and breed them. The flies were kept in aquarium cages covered by cheesecloth and fed skim milk from a tissue in a petri dish). When they laid eggs (always on the tissue) I placed them in an aquarium filled with what I can only describe as Purina fly chow, which I went with two cups of water. When the maggots pupated I plucked one hundred or so out of the container and placed them in a clean aquarium to hatch.

Once hatched, Jed, myself, and a couple of other grad assistants observed their grooming behavior. Flies groom a LOT, so there were mountains of data. Thank goodness, in those pre-microcomputer days I wasn’t the one who had to do the analysis of those data!

Jed was primarily interested in the sequencing of the grooming movements, but I found myself wondering if the purpose was to keep the body clean. To that end I put a fly in a petri dish, covered it with a dollop of flour I had brought from home, waited a couple of days, and looked at them under a microscope. They were no longer covered in flour, which means their grooming in fact moves material about. This paper was the result. I’m not quite sure why I was second author, and I don’t remember the involvement, if any, of authors three and four. I suspect they got their names on the paper because of they worked on the larger fly grooming project. I did all the experiments, and there were no data to analyze. I mean, the flour was observed to be gone, and that was it.

If you’re thinking there must have been a lot of flies in the lab, that didn’t happen. Carbon dioxide knocks them right out. I would play CO2 from a tube attached to a big tank of gas and they would (ahem) drop like flies. I had plenty of times to change their food or remove their eggs before they revived.

We presented the paper at the annual meeting of the Animal Behavior Society.


The Well-Groomed Fly (Musca Domestica)

By E.H. Burtt, Jr., D. Denny, E.J. Molina, & J.M. Howell

University of Tennessee


One possible function of grooming is removal of foreign material from the fly’s body. When a surface is groomed, loose material is picked up by the bristles on the forelegs or hindlegs, whichever is grooming, and some of the material is transferred to the next surface groomed. Hence the route of material flow is predicted by the transition frequencies between grooming patterns.

Predicted routes of material flow were verified by applying flour to different parts of the fly’s body and observing its removal. The results suggest the sequential organization of grooming is independent of peripheral stimulation.