Pam Shanahan, age , of Greenville, Miss., for her question:
WHAT HAPPENS TO THE HOUSEFLY WHEN THE WEATHER GETS COLD?
One of the best known flies is the common housefly. You'll find this insect in almost every part of the world. Adult houseflies live about 30 days during the summer. Most of them die in the winter when the weather gets cold.
There are about 100,000 different kinds of flies on earth. They belong to an order called Diptera, which comes from the Greek word meaning "two wings."
Although the housefly will die after a short life, it will leave eggs to help produce a new generation of flies. The eggs become larvae and pupae, which stay alive during the fall and winter months. These then develop into adult flies when spring arrives.
From one to 250 flies are born at one time, depending on the species. Some female flies are responsible for 1,000 newborn flies in a year. The female drops eggs on water, on the ground and sometimes on animals.
A housefly's eggs will hatch in eight to 30 hours, and out will come a larva which is sometimes called a maggot or a wriggler. The larva looks like a worm or a small caterpillar. It lives in food, garbage, sewage, soil, water or in living or dead plants and animals.
A fly larva spends all its time eating and growing. It sheds its shell and grows a new one several times as it gets older.
Depending on the species, the larva stage of the fly will last from a few days to two years.
The larva then changes into a pupa. A strong, oval shaped case called a puparium covers the insect's body. Inside the puparium, the larva loses its wormlike look and takes the shape of an adult fly.
The pupa stage of a housefly lasts from three to six days in hot weather and longer in cool weather. Again, the length of time will vary among the different species.
When an adult fly leaves the puparium, its wings are still soft and moist. The air dries the wings, and blood flows into their veins and stiffens them. As soon as the wing tissue hardens, the adult flies away and mates.
As soon as the adult housefly leaves the puparium, it is full size. A small fly grows no larger as it gets older, even though its abdomen will swell with food or eggs.
At the tip of each female fly's abdomen is an organ called the ovipositor. It is here where the eggs come out.
The female housefly usually pushes her ovipositor into soft masses of decaying material and lays her eggs there.
The fly is among the fastest of all flying insects. The buzzing you hear as the fly zooms by is caused by the wings, which beat about 200 times a second. Houseflies can fly at a speed of about 4 1/2 m.p.h.