Insects & Nuisance

Flies

Every year, the Environmental Health Services receive complaints about fly infestations, particularly during the summer and autumn months. Flies are common in rural areas where there are poultry farms, stables and piggeries, which provide an abundant supply of manure in which they can breed. This makes the tracing of a particular infestation very difficult and time consuming. There are many types of fly but the following are the most common cause of problems:

Common House Fly (Musca domestica).
Lesser House Fly (Fannia canicularis).
Autumn Fly (Musca autumnalis).
Cluster Fly (Pollenia rudis).

The Common House Fly
The female house fly an lay 120-150 eggs at a time and, depending on the temperature, the eggs can hatch into maggots within 8-48 hours. The maggots then burrow into a food source. The new fly can emerge any time from four days in the summer months, to several weeks in the cooler weather. In this country, the earliest flies tend to emerge in May and the greatest numbers are usually found during August and September.

Breeding more or less ceases in October, except in heated premises. During the winter, the House Fly's cycle is longer. The flies will breed in suitable indoor places and in decaying animal or vegetable matter, including rubbish heaps and horse manure.

Control: The Common House Fly is best controlled by taking preventative measures at source. Dustbins should be kept clean and all perishable food should be wrapped up. Once flies are in the house, fly papers, although unsightly, are effective, as are some of the 'knock down' sprays.

The Lesser House Fly
The Lesser House Fly has a similar life cycle to that of the Common House Fly, although it does not tend to move between waste matter and human food. It was once common in chicken manure but less so today. It is identifiable by its quick darting movements.

Control: As with the House Fly, control measures should be taken at source. Rubbish tips should be managed properly and any adult flies that emerge can be controlled by daily spraying.

The Cluster Fly
This fly gets its name from its habit of clustering like a swarm of bees. It is larger than the Common House Fly and can be easily identified as it folds its wings over its back.

The Cluster Fly enters a house during autumn to hibernate and leaves again in spring, often causing a nuisance at these times. In the autumn, the flies tend to collect on the outside of buildings on warm elevations and later find their way inside to cluster - sometimes in their thousands - in roof spaces, under tiles and in sash windows.

One building in a row, no different from the rest, may be heavily infested and its neighbour completely unaffected. The Cluster Fly is a parasite of earthworms which are usually readily available in any domestic garden.

Control: To kill the occasional fly, a 'knock down' spray can be effective. When flies are particularly troublesome, fly strips can be hung up in the roof spaces and any dead flies can be cleared up using a vacuum cleaner. Food should be kept covered at all times to prevent contamination.

The Autumn Fly
The Autumn Fly is similar in appearance to the House Fly. Its name originates from the fact that it only appears in houses during the autumn months. This fly breeds in cowpats, in rural areas, where they are in plentiful supply.

Control: Control measures are the same as those for the Cluster Fly.

Insects and Nuisance

Local Authorities now have a duty to take reasonable steps to investigate any complaints of insect nuisance. There is no exact definition to the number of insects required to constitute a nuisance. However, the Department for Environment Food and Rural Affairs has published guidance titled "Statutory Nuisance from Insects and Artificial Light". This guidance states in domestic premises, an occupier will normally experience some irritation if there are five or more flying insects present in any one room at any one time on three successive days". This does not mean this level will necessary constitute a nuisance but it can be considered the lowest threshold worthy of further investigation.

Ascertaining the source of insect nuisance can sometimes be a difficult and lengthy process as flying insects can travel considerable distances. The legislation only relates to any insects emanating from relevant, trade or business premises and does not apply where the source of the problem is a domestic property.

If you wish to make a complaint regarding insect nuisance, it would be helpful if you could start by making a log of the insects, their location and numbers over several days. It would also be useful if you could collect some of the insects to allow a proper identification.

If the source if the insect nuisance can be located, we shall try to work with the responsible person to resolve the complaint informally. However, if it is necessary, we can take legal action to resolve the complaint.

If you wish to make a complaint, or would like further information, please contact the Environmental Protection Team.