We are renting a property in Correze whilst we work on our huge renovation project, which at current progress will not be habitable for some time yet. The rental property is pretty well renovated and warm (ish) and easy to heat unlike 99% of the rentals in this very deprived area of France (Plateau Millevaches).
Due to the mild winter we are plagued by cluster flies. As the house is a rental there is not really anything we can do in the way of modifications.
The house is mainly plasterboard/insulation dry lined with some pierre apparent. The windows are all wooden double glazed with airtight seals
The flies always appear in the windows but I never see them fly there?? I have been around the house with a fine toothed comb and cannot work out where they are getting in? How can they be getting in through the window frames which are airtight?
In our spare room if we leave the windows closed then on a spring like day we can find hundreds in there! As you know French windows seem to be either open or shut with little in the design to have them just slightly open?? (puzzles me)
Is there anything we can do to solve the issue? We have a guest next week staying in the affected room,
** Just to note the north facing exterior wall is the only one unpointed on the outside. Itâs full of cracks and holes between the stones big enough to put a hand in. I am sure it is the reason so many flies are getting in. Nothing we can do about it. If it was my house Iâd point it and seal it up.
We get them from time to time - in our case they had holed up in one of the double glazed units, between the bottom of the window and the frame itself - a whole swarm emerged when I opened the window.
In short they might not be âgetting inâ, they might already be âinâ but you need to find where they are hiding.
They are coming out of hibernation and/or hatching with the warmth. There will be eggs everywhere in teeny, tiny cracks. Hoover like crazy, walls, boxes of sash windows, floors, ceilingâŠ.and keep hoovering them up.
The mad thing is that I can sit working at my computer in front of the window and I never see any flying about. They just magically âappear"in the windowâ I have checked and rechecked, but I cannot figure out where they are getting in?
If we have cold weather they disappear, however cold weather has been rare this winter.
For our renovation we are using hemp lime on the granite walls and this insures it is properly sealed and draft proof. All new floors and beams going in so it will be completely sealed up and insulated. Windows will be better quality too with air vents. The problem with plasterboard drylining is that if the detailing is not perfect there are always gaps.We get cold air coming in from plug sockets at the rental!! Still the house we are renting is way more comfortable and sorted than all the others we looked at. Most around here are unrenovated or done in the 1970âs, with zero insulattion and electric heating = hefty bills!!
As Jane said above, they are already in. They hatch indoors and live indoors. They are very easy to hoover up because they are so dopey. We get them in our cottage/gite. Itâs not a big deal to get rid of them before our first guests arrive late spring.
Cluster flies lay their eggs outdoors on the surface of th soil. When the eggs hatch the larvae go in search of earthworms âŠ
âThe cluster fly life cycle begins when the female flies lay their eggs into damp soil in late summer or early autumn. The fertilised eggs will hatch within a few days and the larvae will instantly pursue earthworms. Earthworms play host in this vital part of the cluster fly life-cycle. Once the larvae find an earthworm they will enter the body cavities of the worm where they will stay for several days. Throughout this period they will feed on the earthworm and when they are of a suitable size they emerge from the earthworm at the pupal stage and will fully pupate after eleven to fourteen days. Commonly the adult flies will emerge in the autumn when the temperature starts to decrease leading to adult cluster flies to search out harbourages from the adverse weather conditions. In the wild this will be inside tree bark and the hollows of dead trees, however, with human habitations increased encroachment upon their natural habitats, Cluster Flies have a new and abundant sources of warmth and shelter for winter hibernation. The adult flies will seek refuge, usually in loft spaces of houses as it is the warmest part of the building. They will hibernate in the cold winter months and will emerge in the spring when the temperature increases. The fertilised females will then lay their eggs into damp soil and the life cycle starts all over again.â
Quote from Cluster Fly Life Cycle | Cluster Fly Products
Mine seem to hibernate within the gaps of the beams above the windows (which someone in the past appears to have filled with a totally inappropriate filler). They are making their annoying buzz at the moment having âarrivedâ yesterday. When the relentless rain stops, I will usher them out with a feather duster as this works for me - then they can go hunting for worms. They always seem quite happy to fly out and only ever cluster on the windows.
The article from @Panache is correct, they are parasitec insects who lay eggs in soil, the larvae/maggots fees on earth worms, they hatch and find a nice warm south, south/easterly surface (your outside wall) to keep their energy levels up. They get into the house as @billybutcher says, through the crevaces around windows.
They are attracted t your house because previous generations have been there before, leaving their sweet-sticky pheromone. It is possible that only one house in a row of terasses could be affected.
I personally never use aerosols or smoke bombs; theyâre fine for flying insects but not hiding insects. Flies can hold their breath for several hours by closing their exoskeleton. Bombs have no or little remenance whereas liquid insecticide can last several weeks.
Before my house became my permanent residence I had one particular window frame that was consistently full of flies. Opened it, hoovered them up, sprayed the insect barrier spray andâŠâŠâŠtouch woodâŠâŠtheyâve never been back.
Is there a particularly good time of year to be using the anti-insect barrier spray? As it would be great to minimise insect populations this year.
Peak times are usually March/April and September/October, but it depends on the the weather, it can vary. It seems that this year theyâre already active.
Insecticides are indiscriminate so should not be sprayed on outside walls. Notwithstanding, they wash off on the first rain entering watersources, which is often toxic to aquatic animals.
