stagnant water
Mosquito invasion: What helps against mosquito larvae in rain barrels and garden ponds?
A typical picture when you take a look in the rain barrel or at the garden pond in summer: mosquito larvae in abundance
© Animaflora / Getty Images
The combination of warm outside temperatures and a lot of precipitation create ideal conditions for mosquitoes, which prefer to lay their eggs in standing water. Why is that and what can you do about it? We’ll tell you.
Whether in the rain barrel, in puddles, in the watering can or in the garden pond: millions of mosquito larvae cavort in the warm summer months, which bring a lot of rain. The smaller the water source, the quicker it will heat up—making it an ideal breeding ground for mosquitoes, which prefer to lay their eggs in warm, stagnant water. One reason for this is that the larvae need mild water temperatures to hatch after just a few days. It then takes up to three weeks before they are fully grown and start looking for fresh blood. During this time, you have the opportunity to avert a plague of mosquitoes by fighting the larvae (naturally).
Fight mosquito larvae in standing water
1st possibility
As already mentioned at the beginning, the mosquito larvae stay in the rain barrel or in the garden pond for several weeks after hatching. Before they leave their breeding ground, they remain on the water surface for a while, as long as they are not yet able to fly. And that’s when you can actively intervene to reduce the population – by breaking the surface tension. This works best with olive, rapeseed or sunflower oil, alternatively washing-up liquid also works. It is best to proceed as follows:
- vegetable oil: First of all, you should know that oil on the water surface goes rancid faster if it is exposed to direct sunlight. Therefore, you should only use this method on rain barrels that are in the shade. Take two to three tablespoons of oil, add it to the rainwater and stir it so that the oil film is better distributed.
- detergent: It is best to use a biodegradable product (e.g. from Ecover or So nice) so that you can then use the rainwater to water your plants. Put a maximum of one tablespoon of the washing-up liquid in the water butt to lower the surface tension.
DANGER: Please do not use these two control methods in a garden pond, as there are many species of life (plants and animals) in it.
2nd possibility
Another way to combat mosquito larvae is to use biological control agents for water butts, garden ponds and other bodies of water. Two preparations are mentioned here as examples which – according to the manufacturer – should not have any negative effects on other aquatic organisms such as fish, dragonflies, frogs or plants. “Neudomück mosquito-free” von Neudorff contains ten tablets, one of which is sufficient for 1000 liters of water and has an effect for up to four weeks. There are alternatives Culinex tablets with biological active ingredient (Bacillus thuringiensis israelensi) to combat mosquito larvae. One tablet should be enough for up to 50 liters of water. You can find out how exactly the two preparations are used on the packaging.
3rd possibility
Without the addition of tools, it is possible to contain the mosquito population by removing the larvae in the garden pond or in the rain barrel with a (preferably fine-meshed) landing net fish manually on the water surface. However, since the stinging offspring are quite quick on the move, you will not catch them all in one fell swoop. For this reason, it is advisable to repeat this process over and over again for several days in a row. You can dispose of the larvae in the compost.
How to prevent mosquito larvae in rain barrels
You can take three preventive measures, such as:
- Close the rain barrels with a suitable lid and only open them when it rains. On dry, warm and humid days, the irrigation water should be out of reach for female mosquitoes so that they cannot lay eggs in it.
- Alternatively, you can also use an individually adjustable rain barrel net use to repel mosquitoes. It is particularly fine-meshed so that no insects or leaves get into the water, but raindrops still go through.
- If you empty the water butt regularly, for example because you use up the water to water your plants, there is little risk of mosquito larvae fully developing in it – since they take up to three weeks to become able to fly.
Another note: If you have a Pump in the garden pond use, the water remains constantly in motion and is therefore said to be significantly less attractive to mosquitoes, which prefer standing water to lay their eggs.
That is why mosquitoes are important for our ecosystem
Even if nobody likes the stinging pests, we would like to emphasize at this point that mosquitoes and their larvae are important for our ecosystem. They serve as an important basis of life for many animals such as frogs, birds, spiders, newts, fish and dragonflies. “Even if they are annoying, mosquitoes and their relatives are an important node in the food web,” says Sönke Hofmann, Managing Director of Naturschutzbund Deutschland e. V. (NABU for short). His clear recommendation is: “Anyone who wants to fight mosquitoes should dry out the breeding grounds instead of fogging them with chemicals,” advises Hofmann.
source: NABU Bremen
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