FROM WIKIPEDIA and other sources available on my laptop Apple computer search engine I found all the answers I could have hoped for, as follows:
The housefly (also house fly, house-fly or common housefly), Musca domestica, is a fly of the suborder Cyclorrhapha. It is the most common of all domestic flies, accounting for about 91 percent of all flies in human habitations, and indeed one of the most widely distributed insects, found all over the world. It is considered a pest that can carry serious diseases.
Each female fly can lay approximately 500 eggs in several batches of about 75 to 150. The eggs are white and are about 1.2 mm in length. Within a day, larvae (maggots) hatch from the eggs; they live and feed on (usually dead and decaying) organic material, such as garbage or feces. They are pale-whitish, 3–9 mm long, thinner at the mouth end, and have no legs.
Their life cycle ranges from 14 hours to one week. At the end of their third instar, the maggots crawl to a dry, cool place and transform into pupae, colored reddish or brown and about 8 mm long. The adult flies then emerge from the pupae. (This whole cycle is known as complete metamorphosis.)
THE ADULTS live from two weeks to a month in the wild, or longer in benign laboratory conditions. Having emerged from the pupae, the flies cease to grow; small flies are not necessarily young flies, but are instead the result of getting insufficient food during the larval stage.
Some 36 hours after having emerged from the pupa, the female is receptive for mating. Copulation takes a few seconds to a couple of minutes. Normally, the female mates only once, storing the sperm to use it repeatedly for laying several sets of eggs.
Housefly pupae are killed by parasitic wasp larvae. Each pupa has one hole through which a single adult wasp emerged; feeding occurs during the wasp’s larval stage.
The flies depend on warm temperatures; generally, the warmer the temperature, the faster the flies will develop.
The housefly is an object of biological research, mainly because of one remarkable quality: the sex determination mechanism. Although a wide variety of sex determination mechanisms exist in nature (e.g. male and female heterogamy, haplodiploidy, environmental factors), the way sex is determined is usually fixed within one species.
HOWEVER, the housefly exhibits many different mechanisms for sex determination, such as male heterogamy (like most insects and mammals), female heterogamy (like birds) and maternal control over offspring sex. This makes the housefly one of the most suitable species to study the evolution of sex determination.
Even though the order of flies (Diptera) is much older, true houseflies are believed to have evolved in the beginning of the Cenozoic era, some 65 million years ago.They are thought to have originated in the southern Palearctic region, particularly the Middle East. Because of their close, commensal relationship with humans, they probably owe their worldwide dispersal to co-migration with humans.
With numbers like that, the houseflies are laggards at Upshur Manor. For that I owe thanks to an efficient management.