November Pest of the Month: Cluster Flies

As the temperature drops in the autumn months and we see the first frost of the season, many creatures seek shelter from the cold, and insects are no exception. Cluster flies, or Polleniarudis in their Latin name, seek refuge from the weather, finding cracks and crevices in warm homes to hibernate, especially in loft spaces. They become active again in the spring. As the name suggests, there will be more than one fly; they gather in a cluster. Cluster flies are larger than other house flies and do not bite like others do. They are considered pests due to the annoying volume in which they inhabit homes. Urban Pest Control is always happy to discuss and offer advice to solve any size of cluster fly infestation.

Interesting facts about cluster flies

• Cluster flies are 6-10mm in size.
• They have yellow/golden hairs on their thorax and a chequered pattern on their abdomen. Their wings overlap when they rest.
• Cluster flies are attracted to light.
• They lay eggs on damp soil or rotting leaves, and the eggs hatch within a few days.
• There are usually two generations of cluster flies at one time; however, with the warmer summers in recent years, there can be up to four generations of cluster flies.
• Adult cluster flies feed on flower nectar, plant sap, and fruits. The larvae, which look like tiny white worms, are parasitic to earthworms.

How to recognise you have a cluster fly issue

• Cluster flies prefer to live outside, close to the ground. However, during the autumn and winter, they seek warmth in homes, especially in loft spaces and wall cavities. You may find some dead flies in these areas, and the dead flies also attract other pests such as beetles, which you may notice before the cluster flies.
• Cluster flies become active again in the spring, often looking for a way out of your home. They head towards the light, but due to their size, the cluster may be alarming.
• Cluster flies leave tiny, dark spots of excrement on walls and windows. Although harmless, it looks unsightly and is difficult to clean.

How to prevent cluster flies

• When the weather drops, cluster flies will search for warmth. They enter buildings through loose seals in doors or windows, vents, loose electrical outlets, or cracks and wall crevices before heading to the loft space. The best way to prevent them from entering your property is to seal any cracks or gaps, especially during autumn, but this may need to be repeated in the spring.
• Fly sprays may work on direct contact with active flies, but it is unlikely to make contact with the whole cluster. Vacuum any flies that you find on the ground to remove them. Store-bought sprays will have no effect on hibernating flies.
• In commercial buildings, the sight of cluster flies gathering around windows isn’t pleasant and may give your business a bad reputation, so a swift solution is critical.
• Before any treatment is conducted, the property must be checked for bats, as all bats in the UK are protected under the Wildlife and Countryside Act 1981. It is illegal to use any insecticides that may come into contact with bats.
• If cluster flies are a persistent issue, the best solution is to hire a professional pest controller. Their trained eyes will be able to identify entry points.

Urban Pest Control has various methods to eradicate a cluster fly problem and is happy to provide a quote for an effective solution. The treatment methods used depend on the size of the infestation. All treatments adhere to COSHH regulations 2002. An experienced, qualified, professional pest controller like ourselves will have access to a wide range of industry insecticides and equipment, such as an exodus ULV system, a high-quality fogging machine that enables us to get deeper into the cracks and crevices to target problematic areas. One treatment is often enough to deal with the main infestation and reduce numbers; however, with ‘new flies’ constantly emerging, it is not always possible to completely eradicate all flies. Because of this, it is recommended that a premises should be treated twice a year due to the cluster fly life cycle and hibernation habits.

Should you require more information on cluster flies or are in need of pest control in Poole, Bournemouth, Christchurch, Dorchester, Weymouth, and all surrounding areas, please do not hesitate to contact us.