TheHouseFlyDAMAGED

[Music] Muska domestica. These Latin words are the scientific name for one of the most dangerous insect pests no demand. The common housefly, as its name implies, plagues the households of mankind around the world. It cannot bite or sting, but its physical structure and feeding habits make it a carrier of disease and death. It spreads the organisms that cause typhoid fever, dysentery, tuberculosis, leprosy, hookworm, chalera, diarrhea, anthrax, gang green, and numerous other painful diseases and parasites that inflict suffering and death upon mankind. If the housefly were not such a restless explorer of everything in sight, it would not be such a dangerous pest. But it is equally at home as it visits back and forth between surroundings of finery and places of filth. Before arriving in this spotlessly clean kitchen, flies may visit along the way such places as an unsanitary privy, a decaying animal carcass, or an open dump where disease germs thrive in trash and garbage. Tests have proven that flies from a dump such as this are capable of flying as far as 20 m away to a light perhaps on baby's birthday cake. And while baby may find swatting at flies an amusing part of the celebration, these germladen flies may bring her the unwanted gift of a bad tummy ache. [Music] [Applause] The two main factors which make the housefly such a menace to human health are its structural characteristics and its rapid rate of reproduction. First, let's consider some of the important structural features of the housefly. It is a true insect. It belongs to the order of insects named dipa which means two-winged. Its two transparent wings fold back to give it a triangular appearance when not flying. Bristle-like hairs cover parts of the fly's body. These hairs are one of the means by which the fly picks up and transports millions of disease germs as it visits sources of contamination. Being a true insect, the housefly has three distinct body parts: a head, a thorax, and an abdomen. The head bears the eyes, antenna, and mouth parts or probosus. The surface of each of the large compound eyes is divided into approximately 4,000 facets or individual lenses. The eyes of the male housefly are spaced closer together than those of the female. Between its compound eyes, the housefly also has three oeli or simple eyes. But in spite of this elaborate equipment foreseeing, the housefly depends mainly on its highly sensitive antenna in detecting odors which are attractive to it. The interesting feeding organ or probosus can be retracted almost completely into the head when not extended for feeding. The end of the probosus is a spongy heart-shaped structure composed of two lips or labella which the fly presses against any substance upon which it desires to feed. Disease germs and parasites may adhere to the labella as the fly feeds. They may then be carried to the next place the fly visits and deposited as the fly tastes or feeds on the new substance. The wings and legs of the fly located on the thorax provide excellent locomotion for the fly in its incessant explorations. Both wings and legs in contacting filth become important factors in the disease spreading activity of the fly. Each of the flies feet is equipped with a pair of claws which are used for clinging to rough surfaces. Some segments of the legs and feet are sensitive to taste. On each foot, we see from beneath a light colored structure. These are the pvilli. The pvilli have the special function of making the fly's feet stick to smooth surfaces. Thus, the fly can walk upside down on the ceiling or climb walls with ease. This feature, although helpful to the fly, makes the fly a more dangerous transmitter of disease since its sticky feet pick up germs and parasites and distribute them everywhere the fly walks. Here we are letting a fly walk across a specially prepared gelatin plate. This fly's feet are scattering the spores of a fungus picked up from some surface on which it has walked. Under the microscope a few days later, we can see the rapidly developing fungus as a mass of thread-like branches. Disease germs are spread and multiply in the same manner. The houseflyy's respiratory and digestive systems extend through the thorax and the abdomen. The abdomen also encloses the reproductive system. Breathing is accomplished through holes or pores called spiracles in the body wall. The feeding and digestive systems of the fly add still another manner in which the fly spreads disease. Here we have an animated diagram to give us an idea of how the digestive system functions. When necessary, the fly pumps saliva from its salivary glands onto its food to help soften it. Oftenimes it also regurgitates partially digested food from its crop to help liquefy food it wishes to eat. The probosus then sucks up the food germs included into the esophagus. The pro ventriculus directs the flow of food into the crop. Supposing this fly were to elite next on your strawberry Sunday. The filthy germinfested food in the fly would be regurgitated. The fly's feet would add more contamination. A single housefly has been known to carry over 6 and 12 million bacteria at one time. It becomes obvious why house flies are such a health menace. After being predigested in the crop, the housefly passes its food a little at a time from the crop and the proventriculus now opens the passageway to the stomach. As digestion is completed, the waste products are expelled through the digestive tract. Still laden with the germs or parasites swallowed by the fly. The familiar fly specks are the regurgitations and feces of flies. Many of them may be deposited close together on surfaces frequently visited by flies. House flies lay their eggs anywhere they find the kind of media or food on which the fly larve can feed when they hatch. An uncovered dirty garbage can is an open invitation to breeding flies. Fly larve or maggots are a common sight in unckempt garbage cans. Accumulations of animal refues are also ideal breeding places for flies. Thousands of fly eggs may be laid in a manure pile within a few hours after the manure is dumped. Here you see masses of the tiny white fly eggs. The heat given off by the decaying refues helps to incubate the eggs. The female fly has a long tube or overositor through which the eggs are laid. A single house fly lays an average of 100 to 150 eggs at a time and may lay up to seven batches of eggs in an average lifetime of 2 or 3 weeks. The pearly white eggs are so tiny that 150 of them can rest on a pencil point. In warm weather, the eggs usually hatch within 8 to 24 hours. A slit appears in one end of the egg and the tiny white legless larvae or maggot wriggles out of the egg case. The maggots immediately commence feeding on the decaying food matter in which they find themselves. Within an average of 5 to 14 days in temperate zones, they will be fullrown larve. While they are growing, they go through three distinct laral stages called instars. At the end of each of the first two stages or instars, the maggot molts its skin. When ready to mol, the old skin breaks open at the head or pointed end and slips off as the maggot crawls away. The maggot has hook-shaped mouth parts for feeding and to help it crawl. We have placed the maggot on this stick to see the crawling action more clearly. And now let's watch this action in slow motion. The maggot extends its body forward, anchors its hook-shaped mouth parts, and by muscular contraction pulls its body forward. Maggots have no antenna or eyes, but they are sensitive to light rays, and they immediately seek to find cover when exposed to light. The black dots on the tail end are spiracles through which the maggots breathe. When fully grown, the maggots reach a length of 1/3 to 1/2 an inch. Soon thereafter, they move to a nearby drier area to pupate. Here, the last skin of the maggot shrivels up and becomes the brown seedlike protective coat of the pupa. We will now see by time-lapse photography how the color of the pupa changes. In summer temperatures, the pupil stage lasts an average of 5 days. Larve which pupate in late fall may remain in the pupil stage until the following spring. When the transformation from larvae to fly has been completed, the fly pushes off the end of the pupil case. Here we see flies breaking out of their pupil cases, aided by their expanders. The expander is a sack located on the head of the fly. When it is time for the fly to emerge, body juices inflate this sack, causing the pupil case to split open. When the fly's head is free, it struggles out of its pupil case. Sometimes the emerging flies find it necessary to work their way up through debris, such as leaves, manure, or sand that has covered them during the pupation period. The fly's expander sack then comes in very handy. By alternate expansion and contraction of the sack, the fly is able to open a passageway ahead of itself and with the aid of its legs, it can escape to the surface. After the fly emerges from its pupil case, its exoskeleton hardens. Body juices flow into the wings to expand them. The transparent wings stiffen as they dry. The fly's various body parts take on their characteristic coloration. The fly's expander disappears, being withdrawn into the head, never to be seen or used again. Now, a new generation of flies is ready to carry on the spread of filth and disease. Not too many flies heeded that age-old invitation. Come into my parlor, said the spider to the fly. Since there are not sufficient natural controls to effectively reduce the fly population, man must assume the responsibility for stopping this notorious public health enemy from wandering at will in our communities. But swatting flies one by one while millions of new ones are hatching will never begin to solve the fly problem. Insecticide sprays, though they are a great help in killing flies, are only a part of an adequate control program. Research laboratories are constantly seeking for new methods and insecticides to control house flies. This entomologist is using nuclear equipment to test the food preferences of flies. But sanitation is the only sure cure for the housefly menace. And sanitation begins at home, each citizen's home, and with each citizen's personal habits of cleanliness. While this housewife properly maintains a high standard of cleanliness, she may still be plagued by the flies, which are bred in the filth of a distant neighborhood or a farm where sanitation is not practiced. These flies represent not only a potential danger to human health for miles around, but to the livestock on this and surrounding farms as well. Flies transmit a number of diseases and parasites from infected animals to healthy ones. Thus, it is obvious that a serious and far-reaching community responsibility rests upon each citizen to practice good sanitation habits. For example, to keep the fly population down, poison bait is regularly distributed around this dairy barn. And of course, there is no excuse for anyone helping to create such an unsightly and unsanitary mess as this roadside dump. All waste products should be completely burned or buried. In the city, disposal of waste products such as garbage, trash, and sewage becomes a costly operation. Most cities and towns have sanitation departments in modern facilities for proper waste disposal. After being collected in sanitary trucks, trash and garbage is transported to municipal dumps. In some cases, it is used as fill for low or swampy land areas. By being buried, it is not only out of the reach of flies, but it sometimes helps to reduce the cost of garbage collection through the increased value of the filled land. Some municipalities consume garbage in huge incinerators. In most areas, treatment plants process and sterilize raw sewage before dumping it into our waters. This means cleaner lakes and streams and in turn cleaner recreational areas with fewer flies, less chance of disease, and better fishing. Since raw sewage is as destructive to fish as it is attractive to flies. While civic sanitation agencies have made good progress in a step, only the cooperative action of each individual can ensure final elimination of the health menace represented by this prolific pest.