The flying insects encountered in urban and industrial premises can be of many types but it is generally accepted that those which are regarded as pests are those which —

The insects most associated with the spread of disease in domestic, commercial and industrial premises are the true pest flies.

There are many thousands of species of flies, however, relatively few interact with humans. Those that do are among the most destructive of pest species, spreading diseases to man and domestic animals as well as contaminating food and packaging.

The mobility of flying insects is the primary reason why their status as pests is so important. This allows them to visit many diverse and contaminated habitats within the course of their relatively short life span.

FLIES AS A HEALTH HAZARD

Flies have, over the years, been incriminated many times as potential vectors of food poisoning organism.

Most flies breed and feed in unsanitary conditions where their larvae feed on decaying organic matter; female flies choose suitable areas of rotting vegetation and decaying animal matter in which to lay their eggs. Adults emerge from the pupae in these unsavory sites and in the process can become contaminated with disease-causing agents. The adults then often move into sensitive areas where human food is prepared, processed or consumed, to look for their own food.

The potential for contamination of human food with disease-causing agents has been proven over the years and these agents are able to survive on the outside body surfaces of the flies, particularly among the numerous hairs. They also survive in the flies' gut and in their blood system.

Among the most dangerous of the disease-causing bacteria that have been found on flies are Listeria, Salmonella, Shigella, Cryptosporidium, Klebsiella, Campylobacter, Streptococci, Chlamydia and Escherichia coli.

A recent study carried out at the University of Florida found that nine pathogens could be discovered on flies in Florida restaurants. The researchers grew cultures from flies collected at the back door areas and rear dumpsters of four restaurants in Gainesville, Florida, and within hours the samples were swarming with nine pathogens. Researchers found pathogens that can cause peritonitis, diarrhoea, typhoid fever, bacillary dysentery and possibly staph infection. The flies also carried Escherichia coli and Shigella sonnet.

Food poisoning outbreaks can occur from a minute dose of bacteria. In these cases, the disease could easily have been spread by flying insects — a fact which is rarely understood or appreciated.


PRINCIPLES OF FLY CONTROL

Before any detailed strategy is worked out for the control of flying insects, the most fundamentally important task is to correctly identify the species that is to be controlled.

Setting up control measures that are inappropriate can waste a great deal of time and money because the insect has not been identified correctly.

Having identified the insect, the key to effective control is to pinpoint within the life cycle a vulnerable stage for control. This means that it is not worthwhile developing a control strategy for, say, the egg stage of the insect if that egg stage only lasts a few hours, as it does with flies — the chances of catching the egg are so remote the intervention would be worthless. When the vulnerable stage or stages have been identified, then a control strategy should begin.

A thorough inspection of the premises and the surrounding area is essential. Those working there will be asked about actual and perceived problems then complete a thorough survey of all areas, setting your own agenda and asking your own questions. Useful tools to take would be a spatula, flashlight, screwdriver, etc.

Since the pupae are stationary, locating pupua or pupal casings are key indicators of a breeding site. For the flies, the vulnerable stages that should be considered as targets for control strategies are the larval stage and the adult stage.


LARVAL CONTROL

The larvae of most of the flies that are public health pests are found living and feeding in rotting organic matter, which can be of animal or plant origin. Control strategies can be developed by chemical treatment of the area and medium in which the larvae are to be found.


ADULT CONTROL

The control of adult flies can be considered in two categories – physical and chemical measures.

The chemical treatment of adult fly populations with insecticides has limited use. There may be some occasions when the presence of large numbers of adult flies requires that a space treatment should be carried out, but in general there is little point in using an insecticide to kill a few flies. It is expensive, non- residual and undesirable, particularly in food preparation and food retail outlets.

Physical measures to control adult flies can be divided into two categories — the prevention of entry and trapping.


PREVENTION OF ENTRY

Keeping adult flies out of the premises is one way to control them but it is also extremely difficult to do effectively. The use of door screens, air curtains and window screens has often been successful but these methods frequently suffer in their effectiveness because of staff intervention. Often doors and screens are left open and air curtains not turned on at the beginning of the business day.


TRAPPING

If adult flies do enter the premises, then it is generally possible to trap them in a number of ways. When using traps to control adult flies you are exploiting the senses of the fly. Adult flies navigate throughout their habitat using, in particular, their senses of sight and smell. If you make a trap to attract them visually and then add an odour to it, you are then making use of both of the flies' senses.

Fly traps that use ultraviolet (UV) light as an attractant are the most successful at attracting a wide range of flying insect and they have become the industry standard for fly control throughout the world.

Integrated Pest Management & Pesticide Safety | Spiders | Timber Borers | Flies | Rodents | Cockroaches | Fleas | Fabric Pests