The adult female begins laying eggs in filth such as manure, garbage,
rotting fruit or vegetables, and decaying organic matter after she is 48 hours old. During
a lifetime of about 30 days, the female housefly lays an average of 1,000 eggs.
Depending upon temperature and other conditions, the egg stage lasts
from 5 to 36 hours.
Newly hatched larvae (maggots) move about, feed on the surrounding
organic matter, grow rapidly, and, after about 5 to 8 days, migrate to drier soil or stand
The pupal stage lasts from 4 to 7 days, and from it the fly emerges as a
full-grown adult and crawls upward through the loose soil to the surface.
Soon after, its wings dry and harden, and the fly is ready to start feeding.
Figure 5-9. Life cycle of common housefly, Musca domestica.
b. Fifth Flies As Disease Transmitters. Filth flies have no biting mouth-parts
and cannot take up solid food.
(1) Flies transporting pathogens. To dissolve solid food, the fly vomits onto
the food, then sponges up the mixture, usually defecating in the process.
The fly's proboscis and legs are covered with fine hairs to which bits
of filth cling.
The sticky substance on the fly's feet, which helps it to rest on walls
and ceilings, also picks up bits of food.