Thursday, Aug. 28, 2003
* Japanese name: Kuroi ebae
* Scientific name: Musca bezzii
* Description: Face flies are similar to common house flies, but they are larger and darker. If in doubt, check the eyes: Those of the face fly almost touch at the top, but those of house flies have a wider gap between them. The face of the face fly has a velvety stripe on each side and the body has a silver sheen. Like all true flies (Diptera), face flies have only one pair of wings. In dipterans the second pair has been reduced, by evolution, to a pair of tiny structures like drumsticks, which act as gyroscopes when the insect flies. Thus the fly is able to make high-speed, accurate changes in its flight path if it encounters a disturbance (such as a human trying to swat it).
* Where to find them: Face flies are common on farms and near cattle, because that's where their food is.
* Food: Adult face flies earn their name from the place they go to eat. They sit on the faces of horses and cows and feed on the secretions around the eyes and nostrils. The hapless creatures suffer great discomfort from the attentions of the face fly, but are unable to do much about it. Though the adults are nourished by mucus, the larval diet is more unpleasant still: fresh manure. In summer, eggs are laid in the manure. The pale yellow larvae live and feed in dung until they are mature, after which they pupate in the soil under the manure.
* Special features: When temperatures start to drop after the summer months, adult face flies may congregate on the walls of buildings. Warmed by the sun (especially on south-facing walls), face flies become active and have been known to infest buildings, sometimes in large numbers, especially buildings on or close to farms. During winter, the flies often hibernate on the walls of homes, too.