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In Germany there are about 45 species of Calliphoridae. Blowflies lay their eggs in our gardens, among other places. In their multitude, they often become a plague.

In a nutshell

  • Blowflies find good places to lay their eggs in the garden
  • they prefer intensely smelling, organic storage locations
  • an infestation is annoying and a health hazard
  • Prevention is better than fight

The background

Blowflies are found everywhere in nature. They live on nectar, pollen, honeydew and fungi. Blowflies lay hundreds of eggs to reproduce. When laying eggs, they prefer protein-rich and organic substances so that the offspring are well cared for. Larvae then hatch from the eggs and develop into flies. The animals rely on their sense of smell when choosing where to lay their eggs. They prefer strong-smelling scents, which humans tend to find repulsive. For example the scent of:

Source: Vengolis, Blow-fly 4856, edited from Plantopedia, CC BY-SA 4.0
  • rotting fruit
  • animal droppings
  • decaying plants
  • standing water
  • animal carcasses

Favorite spots in the garden

In our home gardens, the flying insects always find places to lay their eggs. In the most common cases these are:

  • the compost heap
  • long grass
  • the rain barrel
  • the garden pond
  • Fallen fruit posts

Notice: The flies also prefer well-tempered and dark locations.

From egg to fly

Blowflies lay clutches of up to 600 white eggs, which are laid in bundles. They are similar in shape and color to grains of rice, but thinner and slightly longer. A bundle can be of different sizes. Depending on the number of eggs, the size varies between a 1 cent piece and a 2 euro coin. Small, white worms then develop from the eggs: the maggots. This can happen very quickly. It takes between 30 minutes and 24 hours for the larvae to hatch. These then develop into flies within about ten days.

Notice: Blowflies are most active from April to October. If you see a bunch of eggs, you will definitely recognize them.

Act preventively

In order to avoid an infestation with the annoying insects, you can effectively prevent them. This is easier than getting rid of the animals once they are there. Preventive measures aim to ensure that the flies do not lay their clutches in the home garden because there is no suitable place there or they find repellent characteristics. You can take the following preventive measures:

  • Avoid tall grass by mowing regularly
  • Cover rain barrels and other standing water
  • keep the garden pond moving (e.g. with a fountain)
  • avoid unpleasant and intense odors
  • Collect fallen fruit early
  • Spread the scent of alcohol (the flies don't like it)
  • Do not leave food in the garden
  • Clear away used dishes immediately

There are also some plants that insects don't like. The smell drives them away. You can plant these plants in popular spots:

  • elder
  • lead bush
  • mint
  • lavender
  • basil
  • geraniums
  • tomatoes
  • laurel

Tip: The Venus flytrap devours flies as live food and can act preventively against a fly infestation. Spiders are also natural enemies of flies. If you don't mind, spiders are welcome to lay out their webs in the garden.

fight blowflies

If you spot a nest of flies, maggots, or a high incidence of bluebottles, you can use a variety of methods to combat them. It doesn't necessarily have to be the chemistry club. Follow these steps:

  • Egg clutches and maggots should be removed and destroyed
  • remove the attraction (water, fruit, smells).
  • set up a trap from the hardware store
  • apply natural fragrances (see above).

Tip: You can also divert the flies after acute control. If you just don't want to be too close to home, put a mixture of molasses and cornmeal in a far corner of the yard. The flies will move there soon.

frequently asked Questions

Are blowflies harmful to health?

Yes. The flies appear harmless, but they can cause diseases. They are regarded as hygiene pests and cause gastrointestinal infections, salmonella, pneumonia, tuberculosis, typhoid, cholera and blood poisoning. The pathogens pass through the digestive juices they leave on food and surfaces.

What if I ate fly eggs?

Since flies increasingly lay their clutches on food, it happens that people eat them with them. In general, you should therefore check your food carefully before eating it. If it does happen, the eggs usually die from the stomach acid. In rare cases and in children, the sick and the elderly, it can cause health problems. If you feel sick or develop gastrointestinal problems, see your doctor.

Are the insects useful too?

Even if flies are annoying and sometimes a health hazard, they are useful for nature. They are an important part of the food chain, feeding reptiles, amphibians, birds, fish, spiders, dragonflies, wasps and small mammals. And with larvae, flies decompose organic matter and contribute to the formation of humus.

What to do with flies on the compost?

If your composter is heavily infested with flies, it is probably too wet. A rot develops that attracts flies. To keep the compost drier, place newspaper, egg cartons, bark mulch, fallen leaves, or wood chips between the kitchen scraps and the cut lawn. There are also ecological pesticides on the market that break down odors and prevent eggs from being laid.

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