Rain barrel and garden pond
What helps against mosquito larvae in stagnant water?
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 rainfall creates ideal conditions for mosquitoes, which prefer to lay their eggs in stagnant 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: in the warm summer months, which bring a lot of rain, millions of mosquito larvae frolic in them. The smaller the water source, the faster it heats up – and thus offers 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 mosquito plague by fighting the larvae (in a natural way).
Combating mosquito larvae in standing water
1. Option
As mentioned at the beginning, the mosquito larvae stay in the rain barrel or garden pond for several weeks after hatching. Before they leave their breeding ground, they stay on the water surface for a while until they are able to fly. And that is exactly when you can actively intervene to reduce the population – by breaking the surface tension. This works best with olive, rapeseed or sunflower oil, or alternatively you can use dishwashing liquid. The best way to do this is as follows:
- Vegetable oil: First of all, you should know that oil on the water surface goes rancid more quickly 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 (for example from Ecover or So nice) so that you can then use the rainwater to water your plants. Add a maximum of one tablespoon of the washing-up liquid to the rain barrel to reduce the surface tension.
DANGER: Please do not use these two control methods in a garden pond, as it contains many living organisms (plants and animals).
2nd option
Another way to combat mosquito larvae is to use biological control agents for rain barrels, 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” by Neudorff contains ten tablets, one of which is enough for 1000 liters of water and lasts up to four weeks. Alternatively, there are Culinex tablets with biological active ingredient (Bacillus thuringiensis israelensi) to combat mosquito larvae. One tablet is said to be enough for up to 50 liters of water. You can find out exactly how to use the two preparations on the packaging.
3. Option
Without the addition of any aids, it is possible to contain the mosquito population by trapping the larvae in the garden pond or in the rain barrel with a (preferably fine-meshed) Landing net manually from the water surface. However, since the stinging offspring are quite quick, you will not catch them all in one go. For this reason, it is advisable to repeat this process several days in a row. You can dispose of the larvae in the compost.
How to prevent mosquito larvae in rain barrels
So that you don’t even have to think about whether and how to get rid of thousands of mosquito larvae from your rain barrels, you can take three preventative 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 water used for watering should be inaccessible to female mosquitoes so that they cannot lay eggs in it.
- Alternatively, you can also choose an individually adjustable Rain barrel net to repel mosquitoes. It has a particularly fine mesh so that no insects or leaves get into the watering water, but raindrops still get through.
- If you empty the rain barrel regularly, for example because you use the water to water your plants, the risk of mosquito larvae fully developing in it is low – since they need up to three weeks to become able to fly.
Another note: If you have a Pump in the garden pond If you use them, the water will remain in constant motion and will therefore be significantly less attractive to mosquitoes, which prefer stagnant water for laying their eggs.
That’s why mosquitoes are important for our ecosystem
Even if nobody likes the stinging pests, we would like to stress at this point that mosquitoes and their larvae are important for our ecosystem. They serve as an important basis for the survival of many animals, such as frogs, birds, spiders, newts, fish and dragonflies. “Even though they are annoying, mosquitoes and their relatives are an important node in the food chain,” says Sönke Hofmann, Managing Director of the German Nature and Biodiversity Conservation Union (NABU). His clear recommendation is: “If you want to fight mosquitoes, you should dry out the breeding grounds instead of spraying them with chemicals,” advises Hofmann.
source: NABU-Bremen
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