Why is a fly a pest?

Why many fly species are considered a pest comes down to the very definition of pest. If an organism spreads disease, causes any form of destruction, or is considered a general nuisance with no other purpose, then they are a pest. It's commonly believed that most insects are pests, but this is incorrect, as many species serve a purpose in the ecosystem they reside in.

Take the fly, for example. There are over 120,000 species globally, and most of them have a purpose, so they cannot be considered a pest. Across the UK, we don't have anywhere nearly as many species like that, and it's only a staggeringly low 1% of the total fly species that are considered pests anyway. 

The World Health Organisation has estimated that the common housefly (which is only one of 7,000 species in the UK) can spread up to 65 diseases during its lifespan. Of course, this isn't long as the average adult housefly will live for approximately 30 days, but it's the breeding rate that is the threat. 

These are also aggressive bacterial illnesses caused by the spread of pathogens by flies. Typhoid especially is highly contagious and can take the form of a simple fever at times. Once again, it's important to note any symptoms and stop the spread as efficiently as possible before anything worsens. 

Another type of house fly is the cluster fly, which will more commonly be found in quieter parts of your house. This could be the attic/loft or in the wall void(s). Anywhere that could get warm over winter is ideal, as they need that to hibernate. Cluster flies will also be the type of flies you see around your window and windowsill, as they're attracted to the warmth of the sun and light on brighter days. They will appear darker, almost a dark grey olive, and will generally be slower whilst in flight. 

It's worth checking around your bins and rubbish, for most fly species but especially for Bluebottle flies. They are more scavenger-based and are attracted to dead animals and pet faeces, so if you see a large collection at any point, you may have a dead animal somewhere you're unaware of. 

They're easy to spot and remember, as their name originates from the similarity in colour they hold to tinted, coloured bottles. Fruit flies could also reside around your bins or compost with decomposing fruit within. They can infest around places such as pubs also, and fruit orchards and vegetable orchards. A fruit fly, as with most of these species, will be attracted to any organic matter that is left unattended. These can be easily identified by their red eyes, so keep an eye out. 

However, whiteflies are a threat to your garden or greenhouse. They can cause damage to your greenery and plans but sucking out the sap and depositing eggs onto the younger leaves. They are white and can resemble a wedge shape.

Filter flies, Crane flies, and yellow swarming flies are also considered pests to the UK community but generally offer no more threat than any other species. It's still important to remain wary and put in precautions in the form of pest control before the problem becomes an infestation. 

Flies in and around your home aren't necessarily a bad sign, as we've discussed. Some flies can be offering helpful insect deterrents and will be playing a part in an ecosystem that you're not even aware of. However, if you're beginning to notice larger groups or clusters, especially around the areas we've discussed, then there could be a fly infestation in your house.

Larvae and maggots are also a large indicator that something is happening, as this implies that fly breeding is being allowed to occur. 

Flies like and need light and water, so check areas around the house or work that fit that criteria. Light fixtures or gutters could begin to get congested, especially if something has died. This will also be amplified in summer due to the increased heat. Flies will be attracted to rotting or decomposing carcasses, so this should be considered as the cause. 

If you're noticing an increase in dead flies as well, don't take this lightly. If they're getting into your house and are dying, then there's probably a reason they're coming inside in the first place. If you're concerned about large numbers of flies within your home, you must contact the British Pest Control Association (BPCA). 

Fly Prevention

Flies will get into your house no matter what precautions you put into place, and it will be near impossible to get rid of them forever. However, you can do things to stop this from becoming an overwhelming problem for you and your family. The simplest option is to prevent physical access to the flies, such as installing fly screens in and around your kitchen. 

Make sure food is covered where possible and ensuring nothing is left out overnight is essential. Close all windows and doors too, and close curtains to further prevent access. A popular and simple means of killing any flies that have managed to get inside is a sticky trap, taking various forms. Essentially, the tape works by attracting flies to it, and the strong adhesive qualities will keep them from flying away, killing them. 

The sticky effect can last up to 8 weeks in some cases. A variety of fly killers and methods are available depending on the situation. If the flies have reached the breeding stage, and you have found a group of maggots or larvae, then simply pour boiling water over the area to kill them.