HOUSE FLY - URBAN INTEGRATED PEST MANAGEMENT

1. INTRODUCTION

The house fly, Musca domestic Linnaeus, is a well-known cosmopolitan pest of both farm and home. This species is always found in association with humans or activities of humans. It is the most common species found on hog and poultry farms, horse stables and ranches. Not only are house flies a nuisance, but they can also transport disease-causing organisms. Excessive fly populations are not only an irritant to farm workers but, when there are nearby human habitations, a public health could occur.

Distribution

          This commonly fly oriented on the steppes of central Asia, but now occurs on all inhabited continents, in all climates from tropical to temperate, and in a variety of environments ranging from rural to urban. It is commonly associated with animal feces, but has adapted well to feeding on garbage, so it is abundant almost anywhere people live.

2. Life Cycle and Description of Fly

The house fly has a complete metamorphosis with distinct egg, larva or maggot, pupal and adult stages. The house fly overwinters in either the larval or pupal stage under manure piles or in other protected locations. Warm summer conditions are generally optimum for the development of the house fly, and it can complete its life cycle in as little as seven to ten days. However, under suboptimal conditions the life cycle may require up to two months. As many as 10 to 12 generations may occur annually in temperate regions, while more than 20 generations may occur in subtropical and tropical regions.

Egg: The white egg, about 1.2mm in length, is laid singly but eggs are piled in small groups. Each female fly can lay up to 500 eggs in several batches of 75 to 150 eggs over a three to four day period. The number of eggs produced is a

function of female size which, itself, is principally a result of larval nutrition. Maximum egg production occurs at intermediate temperatures, 25 to 30⁰C. Often, several flies will deposit their eggs in close proximity, leading to large masses of larvae and pupae. Eggs must remain moist or they will not hatch.

Larva: Early instar larvae are 3 to 9mm long, typical creamy whitish in color, cylindrical but tapering toward the head. The head contains one pair of dark hooks. The posterior spiracles are slightly raised and the spiracular openings are sinuous slits which are complete surrounded by an oval black border. The legless maggot emerges from the egg in warm weather within eight to 20 hours, and immediately feeds on and develop in the material in which the egg was laid.

The larva goes through three instars and a full-grown maggot, 7 to 12 mm long, has a greasy, cream-colored appearance. High-moisture manure favors the survival of the house fly larva. The optimal temperature for larval development is 35 to 38⁰C, though larval survival is greatest at 17 to 32⁰C. Larvae complete their development in four to 13 days at optimal temperatures, but require 14 to 30 days at temperatures of 12 to 17⁰C.

Nutrient-rich substrates such as animal manure provide an excellent developmental substrate very little manure is needed for larval development, and sand or soil containing small amounts of degraded manure allows for successful below ground development. When the maggot is full-grown, it can crawl up to 50 feet to a dried, cool place near breeding material and transform to the pupal stage.

Pupa: The pupal stage, about 8mm long, is passed in a pupal case formed from the last larval skin which varies in color from yellow, red, brown, to black as the pupa ages. The shape of the pupa is quite different from the larva, being bluntly rounded at both ends. Pupae complete their development in two to six days at 32 to 37⁰C but require 17 to 27 days at about 14⁰C. The emerging fly escapes from the pupal case through the use of an alternately swelling and shrinking sac, called the ptilinum, on the front of its head which it uses like a pneumatic hammer to break through the case.

Adult: The hose fly is 6 to 7mm long, with the female usually larger than the male. The female and can be distinguished from the male by the relatively wide space between the eyes (in males, the eyes almost touch). The head of the adult fly has reddish-eyes and sponging mouthparts. The thorax bears four narrow black stripes and there is a sharp upward bend in the fourth longitudinal wing vein. The abdomen is gray or yellowish with dark midline and irregular dark markings on the sides. The underside of the male is yellowish.

Adults usually live 15 to 25 days, but may live up to two months. Without food, they survive only about two to three days. Longevity is enhanced by availability of suitable food, especially sugar. Access to animal manure does not lengthen adult life and they live longer at cooler temperatures. They require food before they will copulate, and copulation is completed in as few as two minutes or as long as 15 minutes. Oviposition commences four to 20 days  after copulation. Female files need access to suitable food (protein) to allow them to produce eggs, and manure alone is not adequate. The potential reproductive capacity of flies is tremendous, but fortunately can never be realized.  Scientists have calculated that a pair of flies beginning reproduction in April may be progenitors, under optiminal conditions and if all were to live, of 191,010,000, 000, 000, 000 flies by August.

Longevity is enhanced by availability of suitable food, especially sugar. Access to animal manure does not lengthen adult life and they live longer at cooler temperatures. They require food before they will copulate, and copulation is completed in as few as two minutes or as long as 15 minutes. Oviposition commences 4-20 days after copulation. Female flies need access to suitable food (protein) to allow them to produce eggs, and manure alone is not adequate. The flies are inactive at night, with ceilings, beams and overhead wires within buildings, trees and shrubs, various kinds of outdoor wires, and grasses reported

as overnight resting sites. In poultry ranches, the nighttime1 outdoor aggregations of flies are found mainly in the branches, and shrubs, whereas almost all of the indoor populations generally aggregated in the ceiling area of poultry houses.

According to a study conducted in Texas, USA, breeding site suitability (in descending order), was horse manure, human excrement, cow manure, fermenting vegetable, and kitchen waste. However, another study found that structures containing swine, horse, sheep, cattle, and poultry varied in fly abundance, with swine facilities containing the most and poultry the least. Fruit and vegetable cull piles, partially incinerated garbage, and incompletely composted manure also are highly favored sites for breeding.

3. Damage and Medical Importance

Flies commonly develop in large numbers in poultry manure under caged hens, and this is a serious problem requiring control. Although this fly species does not bite, the control of Musca domestica is vital to human health and comfort in many areas of the world. The most important damage related with this insect is the annoyance and the indirect damage produced by the potential transmission of pathogens (viruses, bacteria, fungi, protozoa, and nematodes) associated with this fly. Pathogenic organisms are picked up by flies from garbage, sewage and other sources of filth, and then transferred on their mouthparts, through their vomitus, feces and contaminated external body parts to human and animal food.

Of particular concern is the movement of flies from animal or human feces to food that will be eaten uncooked by humans. Also, when consumed by flies, some pathogens can be harbored in the mouthparts or alimentary canal for several days, and then be transmitted when flies defecate or regurgitate. These flies are most commonly linked to outbreaks of diarrhea and shigellosis, but also are implicated in transmission of food poisoning, typhoid fever, dysentery tuberculosis, anthrax, ophthalmia, and parasitic worms.

Economic Threshold

The threshold density for determining when to control flies depends on the area where the control measures will be taken. In general, at homes the threshold is very

low and control actions are taken with few flies The complaint threshold density of the house fly at waste management sites may be 150 individuals per flypaper per 30 minutes.

Tolerance of flies depends greatly on circumstances. In sensitive environments such as food preparation and packing facilities, restaurants, and hospitals.even small numbers of flies cannot be tolerated. In the context of livestock or poultry production, however, some flies are inevitable. Serious problems occur when cities or suburban development occur near poultry production facilities, as residents usually will not tolerate the large numbers of flies emanating from such facilities.

4. Method of Inspection

In almost all cases, flies originate outdoors. Because of this, the first step in successful control of any fly problem is determining where the flies are breeding. This involves inspection, sanitation, exclusion, and mechanical and chemical control, as warranted:

Inspection

1. Watch the flies. See where they are landing or resting find out what s attracting them
2. Identify the flies. Understanding whether you are dealing with house flies, blow flies, cluster flies, or other large (or small) flies will determine the type of management needed.
3. If there are a lot of flies, there is probably a breeding site either on your property or a neighboring one. Look for these areas as well.
4. You will temporarily reduce populations by killing the adult flies, but until you get to the source and eliminate the breeding areas you will not have full control.

The following describes outdoor control methods for house flies. If the inspection found it to be a cluster fly or other large fly, or fruit or other small flies, specific control methods will be somewhat different although sanitation and exclusion are key to controlling virtually any pest.