An infestation of flies

On Facebook, Max Meredith Vasilatos has been reporting on her wars with fruit flies in her San Francisco condo. Even when there’s no food out for them to feast on, still they persist. Max has tried to eliminate possible breeding places by pouring boiling water and bleach down the bathroom drains, but still there are flies.

Commenters on Facebook suggest that she is facing, not fruit flies (Drosophila species, especially the common D. melanogaster) in search of fruit (rotting if possible), but drain flies (from one of a large number of species, though the moth fly Clogmia albipunctata is especially widespread) in search of sludge.

I am, of course, familiar with common fruit flies, but also with at least one species of drain fly (though not C. albipunctata), a species that’s a minor summertime nuisance around my house.

Start with the familiar.

 width= (#1)

From Wikipedia:

Drosophila melanogaster is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is known generally as the common fruit fly or vinegar fly. Starting with Charles W. Woodworth’s proposal of the use of this species as a model organism, D. melanogaster continues to be widely used for biological research in studies of genetics, physiology, microbial pathogenesis, and life history evolution. It is typically used because it is an animal species that is easy to care for, has four pairs of chromosomes, breeds quickly, and lays many eggs. D. melanogaster is a common pest in homes, restaurants, and other occupied places where food is served.

But drain flies look quite different. Here’s a C. albipunctata “moth fly”:

 width= (#2)

From Wikipedia:

Drain flies, sink flies, moth flies [or moth midges], or sewer gnats (Psychodidae) are small true flies (Diptera) with short, hairy bodies and wings giving them a “furry” moth-like appearance, hence one of their common names, moth flies. There are more than 4,700 known species worldwide, most of them native to the humid tropics. Moth flies sometimes inhabit human drains and sewage systems where they are a harmless but persistent annoyance.

The larvae of the subfamilies Psychodinae, Sycoracinae and Horaiellinae live in aquatic to semi-terrestrial or sludge-based habitats, including bathroom sinks, where they feed on bacteria and can become problematic. The larvae of the most commonly encountered species are nearly transparent with a non-retractable black head and can sometimes be seen moving along the moist edges of crevices in shower stalls or bathtubs or submerged in toilet water.

… Because of the extremely fine water-repellent hairs covering their bodies, adult drain flies are difficult to drown, and are not affected by contact with most water-borne toxins such as bleach. Boiling water has little or no effect on the adults for the same reason, and even the eggs are highly resistant to both chemical or thermal assault. Eggs can also withstand periods of dehydration. Extermination of this household pest depends on the maintenance of clean household drains for a period of at least three weeks. [For this purpose, an enzyme-based sludge-digesting product is apparently the thing.]

The species was named by someone named Williston in 1893. The name albipunctata ‘white-dotted’ is unchallenging, but I’ve yet to see an account of Clogmia (or information about Williston); a connection to ckogs would be just too perfect.

Meanwhile, here in Palo Alto I am minorly afflicted by a species in the Psychodidae — not furry, plain black, and attracted to moisture. Once summer is firmly upon us, with no rain at all, these little flies will appear on the outside walls of my condo, close to doors and windows, and will fly into the house if given any chance at all — and then head right for the bathroom.

Soon, very soon, they’ll be here.

One Response to “An infestation of flies”

  1. arnold zwicky Says:

    About the Williston I mentioned, David Gold writes in e-mail:

    He was Samuel Wendell Williston, an American entomologist.

    From Wikipedia at

    Samuel Wendell Williston (July 10, 1851 – August 30, 1918) was an American educator and paleontologist who was the first to propose that birds developed flight cursorially (by running), rather than arboreally (by leaping from tree to tree). He was also an entomologist, specialising in Diptera.
    …Although never employed as a professional entomologist, Samuel W. Williston was also a well-renowned specialist on the taxonomy and systematics of flies. He became the first North American specialist on this group, publishing over 50 dipterological publications and naming more than 1250 species. His best-known works were the three editions of the Manual of North American Diptera (1888, 1896, 1908).

Leave a Reply

%d bloggers like this: