The housefly has a tendency of frequent vomiting and defecating while feeding and has the habit of defecating constantly throughout the day. Thus it deposits countless bacteria in the exposed food.
A house fly breeds on human excreta, cow dung, horse manure, refuse collections, decaying and fermenting vegetable and animal matter. It requires moisture for breeding therefore cannot breed in very dry materials. A female house fly lays 100-150 eggs at a time in moist decaying organic matter like human excreta, animal excreta, garbage and vegetable refuse. It lays 5 or 6 such batches of eggs in a season.
The life cycle of house fly has four stages i.e. egg, larva, pupa and adult. The life cycle from egg to adult takes about 10-20 days for completion which depends on temperature.
The greater the temperature and humidity, the quicker the cycle. A house fly can live for more than 15 days in summer and 25 days in winter. In autumn season they are subjected to a natural disease which kills them in large numbers.
Fly Borne Diseases:
Flies are responsible for spreading a large number of diseases like diarrhea, dysentery, gastroenteritis, cholera, typhoid, paratyphoid fever, amoebiasis, trachoma, conjunctivitis, worm infestations, and polio.
Control of Flies:
Fly nuisance can be controlled by adopting following measures:
(a) Prevention of Breeding of Flies:
(i) Promptly remove and properly dispose of human excreta, cow dung, horse manure, refuse and organic matter.
(ii) Do not allow the refuse to accumulate near the habitation specially stables, cow sheds, slaughter houses, fish markets etc. They should be regularly cleaned.
(iii) Do not throw the refuse in the open on roads or streets. Put it in the covered dust bins.
(iv) For destruction of eggs, larvae and pupae of flies in the manure apply some toxic substance to the manure. For this purpose borax, gammexane, chlorodane etc. can be used. DDT does not much have much effect on fly larvae.
(v) Keep as much cleanliness as possible.
(b) Prevention of Flies to Reach Human Excreta:
(i) Human excreta should be disposed of by water carriage system.
(ii) Fly proof privies and latrines provided with self closing seat covers should be used.
(iii) Night soil should be collected in covered fly proof receptacles and disposed of in a sanitary manner.
(iv) Do not defecate in the open. If defecated in the open then excreta must be covered properly with earth or sand to prevent access of flies.
(v) In fairs and camps, deep trench latrines with fly proof seats should be used.
(c) Protection of Food from Flies:
(i) The food should be protected from flies by covering it with wire-gauge or muslin cloth.
(ii) The hawkers and stall owners should cover the eatables with wire gauge, muslin cloth or should keep in glass cases, fly proof almirahs etc. specially prepared for the purpose.
(iii) The doors, windows and ventilators of houses, restaurants, hotels, confectionary stores, hospitals, fish and meat markets should be fitted with wire mesh which will give a considerable relief from house flies and prevent contamination of food by them.
(iv) Electric fans may be used to force a current of air over the food products which will prevent the flies to settle over the food products.
(d) Killing of Adult Flies:
(i) Sticky fly papers, strings or tangle foot are prepared by smearing a hot mixture of castor oil and resin on glazed paper or strings. They are placed in rooms or suspended from walls. Flies stick to them and.die. They are effective as long as they remain sticky. With this method only small number of flies can be reduced.
(ii) Fly traps of different varieties are available in the market. The conical hoop fly trap is most effective and economical. The bait is placed at the bottom of the cone. The flies are attracted towards it due to odour of the bait and trapped inside. Afterwards the flies are killed by fumigation.
(iii) Now day’s electric insect killers are available in the market which are quite effective for killing the flies.
(iv) In small numbers flies are killed by wire mesh or hard flaps of plastic or leather fitted with handles.
(v) Poisonous baits may be used for killing the flies. The insecticides such as DDT, BHC have now become ineffective in killing the house flies largely because the flies have developed resistance to these insecticides.
A poisonous bait of 2% formalin solution with little sugar and milk is placed in the rooms to attract flies, since they are thirstily insects, are always attracted towards water or the solution and die after drinking the poisonous solution.
No fly control measure will be successful unless people give full co-operation in this measure. Public should be convinced through health education that house fly is a carrier of diseases hence they must adopt anti-fly measures.
It has been rightly said that a clean house with clean surroundings can lessen the fly problem to a great extent. So clean habits should be adopted. Houses, surroundings and habitations must be kept clean to decrease the insect problems.