Flying in winter

Summer is over, which means we've finally got rid of those pesky flies in the house. Or have we? Due to our milder climate, we are increasingly bothered by overwintering flies. They are looking for a nice place in a warm house to spend the winter. And often in large numbers. What exactly is the situation?

Can flies

The swarm fly (or cluster fly) owes its name to the fact that it likes to seek the company of hundreds and sometimes thousands of conspecifics. The best-known swarm fly is the blowfly. However, some lesser-known species also appear in winter, which also overwinter in large swarms. We briefly introduce the most common winter swarm flies.

Blowflies (Callophoridae)

Humming fly is a collective term for flies that buzz to disturb our summers. They usually have a metallic appearance, e.g. shiny blue or green. In Europe, we mainly find the red-cheeked buzzing fly and the blue flesh fly. Blowflies are relatively large, almost one centimetre long. They usually hide in cracks and holes to hibernate. For example, in cavity walls, shutter boxes or pantries. This is why they are often only seen on sunny and warm winter days when they are all together on the windows.

Autumn flies (Musca autumnalis)

The autumn fly is mainly found on the outskirts of cities and in rural areas. This is because the females lay their eggs in dung. The adult flies bite to drink blood. They do this mainly on cattle. The autumn fly is slightly smaller than the damselfly. They have a dark yellow body with a black stripe. In winter they gather in buildings, just like the blue butterflies. Especially in villages and industrial areas. You can often find both fungus gnats and bugs in a building.

Grass flies (Thaumatomyia notata Meigen)

Grass flies are like oversized fruit flies. These flies have a bright yellow or green colour. At 3 millimetres in size, they are hardly noticeable. Unless there are hundreds of them in your home. Grass flies love climbing plants such as ivy. Do you have them on your façade? Then there is a good chance that these flies will try to get inside to find a nice place to hibernate. It is particularly important that you seal your joints well.

Keeping winter flies out of the home

If you have an infestation of fungus gnats, you should definitely call in a professional pest controller, otherwise you won't get rid of them! Unfortunately, we find that fungus gnats often infest the same building every year. So how can you make your home less attractive to these winter flies? A fly looking for a place to hibernate only needs a surprisingly small hole to work its way in. Do you have a lot of problems with flies in winter? Then you should think about installing fly screens in front of your windows and/or leaving them in place even in winter. It is also a good idea to check the outside of your house for holes and cracks. For example, seal the gaps between the window frames and the walls. You will also benefit from this in summer!